release change to 1.7.12
Merge branch 'tmp1.7.12' into develop
upgrade to Xtext / Xtend 2.6.0 final
switch to Xtext / Xtend 2.6.0
Merge remote-tracking branch 'origin/develop' into develop-1.7.12
Merge branch 'develop-1.7.11' into develop-1.7.12