SI-5784 Scaladoc: {Abstract,Alias} type templates

Normally scaladoc won't generate template pages for anything other than
packages, classes, traits and objects. But using the @template
annotation on {abstract,alias} types, they get their own page and take
part as full members in the diagrams. Furthermore, when looking for the
companion object, if a value of type T is in scope, T will be taken as
the companion object (even though it might be a class)

All templates, including types are listed on the left navigation pane,
so now adding @template to String can get scaladoc to generate (a
no-comments) page for java.lang.String.

The {abstract, alias} type icons need to be updated -- I just took the
class icons and added a small x to them -- but they shoud be something
else (maybe an underscore?)i

TO USE THIS PATCH:
<pre>
/** @contentDiagram */ // tells scaladoc to create a diagram of the
                       // templates contained in trait Base
trait Base {
  /** @template */ // tells scaladoc to create a page for Foo
  type T < Foo
  trait Foo { def foo: Int }
}

/** @contentDiagram */
trait Api extends Base {
  /** @template */
  override type T <: FooApi
  trait FooApi extends Foo { def bar: String }
}
</pre>

2 files changed, 29 insertions, 0 deletions

diff --git a/test/scaladoc/resources/SI-5784.scala b/test/scaladoc/resources/SI-5784.scala
new file mode 100644
index 0000000000..175cc3cf33
--- /dev/null
+++ b/test/scaladoc/resources/SI-5784.scala
@@ -0,0 +1,28 @@
+package test.templates {
+  object `package` {
+    /** @template */
+    type String = java.lang.String
+    val String = new StringCompanion
+    class StringCompanion { def boo = ??? }
+  }
+
+  /** @contentDiagram */
+  trait Base {
+    /** @template */
+    type String = test.templates.String
+    /** @template
+     * @inheritanceDiagram */
+    type T <: Foo
+    val T: FooExtractor
+    trait Foo { def foo: Int }
+    trait FooExtractor { def apply(foo: Int); def unapply(t: Foo): Option[Int] }
+  }
+
+  /** @contentDiagram */
+  trait Api extends Base {
+    /** @template
+     *  @inheritanceDiagram */
+    override type T <: FooApi
+    trait FooApi extends Foo { def bar: String }
+  }
+}
diff --git a/test/scaladoc/resources/doc-root/AnyRef.scala b/test/scaladoc/resources/doc-root/AnyRef.scala
index 1eefb0c806..7d8b9f9e76 100644
--- a/test/scaladoc/resources/doc-root/AnyRef.scala
+++ b/test/scaladoc/resources/doc-root/AnyRef.scala
@@ -10,6 +10,7 @@ package scala
 
 /** Class `AnyRef` is the root class of all ''reference types''.
  *  All types except the value types descend from this class.
+ *  @template
  */
 trait AnyRef extends Any {