Revert "Upgrade to xtext2.4 (again)"

This reverts commit c6d74091d33c31d356e06e1394ba49014985c08d.
Merge branch 'aaron-dev' of https://github.com/aphethean/IRIS into aaron-dev
Fix a minor issue with RIM visualisation plugin in the Eclipse Indigo release (JRE1.6)
fixes #47 fail the build if any of the RIM source files have errors.