MPS 2.0.6 bugfix release

It seems we rushed 2.0.5 a bit and a nasty bug sneaked in accidentaly. This one really needed to be eliminated urgently. Please, find the fixed 2.0.6 release ready for download. Sorry for the inconvenience.

If you want to see the offending bug, check out the release notes.

Develop with pleasure!
-JetBrains MPS Team