Fix #55 - Async implementation depends on continuations plugin

- remove CPS dependency from default async implementation (fix #55)
- move all CPS-related code to `continuations` sub package
- fix CPS-based async implementation
- enable testing of CPS-based async implementation
Address deprecation warnings in Scala 2.10.1
Address lint warnings.
Temporarily comment out tests that are failing under 2.10.1.
Scala 2.10.1 compat: apply renaming to originals of TypeTrees
Scala 2.10.1 compat: account for change in PartialFunction synthesis.

Since SI-6187, the default case of a partial function is now included in the tree.
Before, it was a tree attachment, conditionally inserted in the pattern matcher.

I had hoped that that change would allow us to do away with
`RestorePatternMatchingFunctions` altogether, but it seems that
we aren't so lucky.

Instead, I've adapted that transformer to account for the new scheme.
Scala 2.10.1 compat: apply renaming to originals of TypeTrees

This time in the ANF/Inline transformation.