Attempt to not crash too badly when a file is deleted from the workspace.
Introduce ScalaInstallation to represent the Scala jars used to build a project.
Merge pull request #691 from dragos/issue/on-the-fly-compiler-interface

Define ScalaInstallation, in preparation for multi-version support
Bumps version numbers
Increase test timeouts (possible source of flaky classpth tests).
Create features for each Scala versions

This will allow to install multiple versions of Scala on
the same Eclipse installation.
The main sdt build phase now only depends on p2 repos, external or local
created in the previous phases.
Some version definition
Tweaks the arguments in the build script
Creates a Scala 210 jars bundle

To be used instead of the normal bundles until when are able to support multiple bundles of Scala
Fixes scala211 source feature label
Adds computeSourcePath documentation
Cleans up new features labels
Merge pull request #690 from skyluc/issue/multi-scala-support

multi Scala support
Adds support to detect available Scalas

Detects both bundled jars and multi-bundles installations
Merge pull request #693 from skyluc/issue/detect-multi-scala

detect multiple scala
Added the ability to compile the sbt compiler-interface on the fly and use it.
Reviewer’s comments.
Fixes memory test configuration

Because the m2 repos are no more used in this part of the build, the
version for the needed Scala jars are no more pre-set.
Merge pull request #698 from skyluc/issue/fix-memory-test

Fixes memory test configuration
Merge pull request #694 from dragos/issue/on-the-fly-compiler-interface-2

Added the ability to compile the sbt compiler-interface on the fly