Undoing some much too hacky code to implement a...

Undoing some much too hacky code to implement a -jar option and then
following wherever that led me. Tangible results include:

 * much beautified scala -help, including documenting some things
   never before documented in this plane of existence
 * an improved Jar abstraction
 * further systemization of system properties

In addition, the jars created by -savecompiled are given the right
manifest so the jar is runnable. That means you can:

  scala -savecompiled bippy.scala arg1 arg2
  scala -jar bippy.scala.jar arg1 arg2

And both lines should yield the same result. No review.

1 files changed, 3 insertions, 8 deletions

diff --git a/src/library/scala/util/control/NoStackTrace.scala b/src/library/scala/util/control/NoStackTrace.scala
index d8cd36aa02..f33e8cd013 100644
--- a/src/library/scala/util/control/NoStackTrace.scala
+++ b/src/library/scala/util/control/NoStackTrace.scala
@@ -10,19 +10,14 @@ package scala.util.control
 
 /** A trait for exceptions which, for efficiency reasons, do not
  *  fill in the stack trace.  Stack trace suppression can be disabled
- *  on a global basis by setting the system property named at
- *  NoStackTrace.DisableProperty.
+ *  on a global basis via a system property wrapper in
+ *  [[ scala.sys.SystemProperties ]].
  *
  *  @author   Paul Phillips
  *  @since    2.8
  */
 trait NoStackTrace extends Throwable {
   override def fillInStackTrace(): Throwable =
-    if (sys.props contains NoStackTrace.DisableProperty) super.fillInStackTrace()
+    if (sys.SystemProperties.noTraceSupression) super.fillInStackTrace()
     else this
 }
-
-object NoStackTrace {
-  // TODO: systematic naming scheme.
-  final val DisableProperty = "scala.control.no-trace-suppression"
-}