Modularize continuations plugin.

The continuations plugin and library will still ship with 2.11 (albeit unsupported).
They now reside at https://github.com/scala/scala-continuations.
Modularize the swing library.

The Scala Swing library will still ship with 2.11 (albeit unsupported).
It now resides at https://github.com/scala/scala-swing.
Merge pull request #3221 from adriaanm/modularize-cps

Final library modularization for 2.11
Fix osgi bundle name for continuations.
Merge pull request #3272 from adriaanm/modularize-cps-fix

Fix osgi bundle name for continuations.
Improvements to partest-ack, plus partest-paths.

I noticed partest-ack was not finding all matching tests, and
fixed that. Also cleaned up the ack options so they're understood
by the latest version of ack.

Along the way I broke the canonicalization functionality out into its
own script so it can easily be used from other places.
Merge pull request #3273 from paulp/pr/ack

Improvements to partest-ack, plus partest-paths.