downgrading from Xtext 2.4.2 (and related EMF & Xcore) tol older 2.3.1,
due to compatibility issues in in-house proprietary product which we
haven't upgraded yet..
re-activating previously failing XcoreTest, because it actually works
with older version (just not with latest released; see reference
Bugzilla)
Kleingemüse
FIX for DS-6421
deactivating Xtend (due to some version dependency issues with for
ongoing downgrading exercise)