Scala Installations support

Adds a valid, persistent, best-effort scala library bundle setup on classpath after the choice of a scala desired source level in project-scopes compiler options.

Operates by modifying and serializing the scala classpath container.

Does not include scala-installation registry edition yet.
There is no point to run the beginning of the test on 2.10 if it cannot be checked.

The previous test doesn't make much sense on 2.10 either, no?