Maven compatible eiqgen "compiler" (generator) and poor man's compiler testing

[istvanrath]

The idea is to perform (automated) compiler testing by integrating our generator as a maven compiler, compiling a concrete incquery project and executing the result in a (stripped-down) Eclipse environment.

[ujhelyiz]

This goal will be achieved in two steps:

1. An Eclipse application will be created by @csattila, that allows executing the clean and full builds of the Xtext-based builder.
2. Then the tycho-eclipserun-plugin will be used to execute this application from the IncQuery build. For an example, see http://eclipseandlinux.blogspot.hu/2012/07/pre-indexing-documentation-with-tycho.html

[ujhelyiz]

The current implementation in the maven-compiler branch features an almost working Eclipse IApplication to be called from Maven by executing the Xtext project builder on a selected project.

However, it does not work because during dependency injection some ResourceProviderServices are to be added to the builder. Either these dependencies are to be managed better, or alternatively it seems possible to to directly call the builder participant, thus skipping the upper layers. To decide that, further experimentation is needed.

[ujhelyiz]

Migrated to https://bugs.eclipse.org/bugs/show_bug.cgi?id=398797