Number files like chapters. Consolidate toc & preface.

Aside from the consolidation of title & preface in index.md,
this commit was produced as follows:

```
cd spec/

g mv 03-lexical-syntax.md                      01-lexical-syntax.md
g mv 04-identifiers-names-and-scopes.md        02-identifiers-names-and-scopes.md
g mv 05-types.md                               03-types.md
g mv 06-basic-declarations-and-definitions.md  04-basic-declarations-and-definitions.md
g mv 07-classes-and-objects.md                 05-classes-and-objects.md
g mv 08-expressions.md                         06-expressions.md
g mv 09-implicit-parameters-and-views.md       07-implicit-parameters-and-views.md
g mv 10-pattern-matching.md                    08-pattern-matching.md
g mv 11-top-level-definitions.md               09-top-level-definitions.md
g mv 12-xml-expressions-and-patterns.md        10-xml-expressions-and-patterns.md
g mv 13-user-defined-annotations.md            11-user-defined-annotations.md
g mv 14-the-scala-standard-library.md          12-the-scala-standard-library.md
g mv 15-syntax-summary.md                      13-syntax-summary.md
g mv 16-references.md                          14-references.md

perl -pi -e 's/03-lexical-syntax/01-lexical-syntax/g' *.md
perl -pi -e 's/04-identifiers-names-and-scopes/02-identifiers-names-and-scopes/g' *.md
perl -pi -e 's/05-types/03-types/g' *.md
perl -pi -e 's/06-basic-declarations-and-definitions/04-basic-declarations-and-definitions/g' *.md
perl -pi -e 's/07-classes-and-objects/05-classes-and-objects/g' *.md
perl -pi -e 's/08-expressions/06-expressions/g' *.md
perl -pi -e 's/09-implicit-parameters-and-views/07-implicit-parameters-and-views/g' *.md
perl -pi -e 's/10-pattern-matching/08-pattern-matching/g' *.md
perl -pi -e 's/11-top-level-definitions/09-top-level-definitions/g' *.md
perl -pi -e 's/12-xml-expressions-and-patterns/10-xml-expressions-and-patterns/g' *.md
perl -pi -e 's/13-user-defined-annotations/11-user-defined-annotations/g' *.md
perl -pi -e 's/14-the-scala-standard-library/12-the-scala-standard-library/g' *.md
perl -pi -e 's/15-syntax-summary/13-syntax-summary/g' *.md
perl -pi -e 's/16-references/14-references/g' *.md
```

1 files changed, 147 insertions, 0 deletions

diff --git a/spec/10-xml-expressions-and-patterns.md b/spec/10-xml-expressions-and-patterns.md
new file mode 100644
index 0000000000..d8c45ecf85
--- /dev/null
+++ b/spec/10-xml-expressions-and-patterns.md
@@ -0,0 +1,147 @@
+---
+title: XML Expressions and Patterns
+layout: default
+chapter: 10
+---
+
+# XML Expressions and Patterns
+
+__By Burak Emir__
+
+This chapter describes the syntactic structure of XML expressions and patterns.
+It follows as closely as possible the XML 1.0 specification,
+changes being mandated by the possibility of embedding Scala code fragments.
+
+## XML expressions
+
+XML expressions are expressions generated by the following production, where the 
+opening bracket `<` of the first element must be in a position to start the lexical
+[XML mode](01-lexical-syntax.html#xml-mode).
+
+```ebnf
+XmlExpr ::= XmlContent {Element}
+```
+
+Well-formedness constraints of the XML specification apply, which
+means for instance that start tags and end tags must match, and
+attributes may only be defined once, with the exception of constraints
+related to entity resolution.
+
+The following productions describe Scala's extensible markup language,
+designed as close as possible to the W3C extensible markup language
+standard. Only the productions for attribute values and character data are changed. 
+Scala does not support declarations, CDATA sections or processing instructions.
+Entity references are not resolved at runtime.
+
+```ebnf
+Element       ::=    EmptyElemTag
+                |    STag Content ETag                                       
+
+EmptyElemTag  ::=    ‘<’ Name {S Attribute} [S] ‘/>’                         
+
+STag          ::=    ‘<’ Name {S Attribute} [S] ‘>’                          
+ETag          ::=    ‘</’ Name [S] ‘>’                                        
+Content       ::=    [CharData] {Content1 [CharData]}
+Content1      ::=    XmlContent
+                |    Reference
+                |    ScalaExpr
+XmlContent    ::=    Element
+                |    CDSect
+                |    PI
+                |    Comment
+```
+
+If an XML expression is a single element, its value is a runtime
+representation of an XML node (an instance of a subclass of 
+`scala.xml.Node`). If the XML expression consists of more
+than one element, then its value is a runtime representation of a
+sequence of XML nodes (an instance of a subclass of 
+`scala.Seq[scala.xml.Node]`).
+
+If an XML expression is an entity reference, CDATA section, processing 
+instructions or a comments, it is represented by an instance of the 
+corresponding Scala runtime class.
+
+By default, beginning and trailing whitespace in element content is removed, 
+and consecutive occurrences of whitespace are replaced by a single space
+character `\u0020`. This behavior can be changed to preserve all whitespace
+with a compiler option.
+
+```ebnf
+Attribute  ::=    Name Eq AttValue                                    
+
+AttValue      ::=    ‘"’ {CharQ | CharRef} ‘"’
+                |    ‘'’ {CharA | CharRef} ‘'’
+                |    ScalaExpr
+
+ScalaExpr     ::=    Block
+
+CharData      ::=   { CharNoRef } $\mbox{\rm\em without}$ {CharNoRef}`{'CharB {CharNoRef} 
+                                  $\mbox{\rm\em and without}$ {CharNoRef}`]]>'{CharNoRef}
+```
+
+<!-- {% raw  %} stupid liquid borks on the double brace below; brace yourself, liquid! -->
+XML expressions may contain Scala expressions as attribute values or
+within nodes. In the latter case, these are embedded using a single opening 
+brace `{` and ended by a closing brace `}`. To express a single opening braces
+within XML text as generated by CharData, it must be doubled.
+Thus, `{{` represents the XML text `{` and does not introduce an embedded Scala expression.
+<!-- {% endraw %} -->
+
+```ebnf
+BaseChar, Char, Comment, CombiningChar, Ideographic, NameChar, S, Reference
+              ::=  $\mbox{\rm\em “as in W3C XML”}$
+
+Char1         ::=  Char $\mbox{\rm\em without}$ ‘<’ | ‘&’
+CharQ         ::=  Char1 $\mbox{\rm\em without}$ ‘"’
+CharA         ::=  Char1 $\mbox{\rm\em without}$ ‘'’
+CharB         ::=  Char1 $\mbox{\rm\em without}$ ‘{’
+
+Name          ::=  XNameStart {NameChar}
+
+XNameStart    ::= ‘_’ | BaseChar | Ideographic 
+                 $\mbox{\rm\em (as in W3C XML, but without }$ ‘:’
+```
+
+## XML patterns
+
+XML patterns are patterns generated by the following production, where
+the opening bracket `<` of the element patterns must be in a position
+to start the lexical [XML mode](01-lexical-syntax.html#xml-mode).
+
+```ebnf
+XmlPattern  ::= ElementPattern 
+```
+
+Well-formedness constraints of the XML specification apply.
+
+An XML pattern has to be a single element pattern. It
+matches exactly those runtime
+representations of an XML tree
+that have the same structure as described by the pattern.
+XML patterns may contain [Scala patterns](08-pattern-matching.html#pattern-matching-expressions).
+
+Whitespace is treated the same way as in XML expressions.
+
+By default, beginning and trailing whitespace in element content is removed, 
+and consecutive occurrences of whitespace are replaced by a single space
+character `\u0020`. This behavior can be changed to preserve all whitespace
+with a compiler option.
+
+```ebnf
+ElemPattern   ::=    EmptyElemTagP
+                |    STagP ContentP ETagP                                    
+
+EmptyElemTagP ::=    ‘<’  Name [S] ‘/>’
+STagP         ::=    ‘<’  Name [S] ‘>’                          
+ETagP         ::=    ‘</’ Name [S] ‘>’                                        
+ContentP      ::=    [CharData] {(ElemPattern|ScalaPatterns) [CharData]}
+ContentP1     ::=    ElemPattern
+                |    Reference
+                |    CDSect
+                |    PI
+                |    Comment
+                |    ScalaPatterns
+ScalaPatterns ::=    ‘{’ Patterns ‘}’
+```
+