removed cycle between utils and typing

Change-Id: Ic4adc776a137fcd24bf1dcc484dc1d93a3e2b54c
28: Use released Xtext 2.7.0

Though we still need to use Xcore 1.3.0 from the EMF nightly site.

Change-Id: I88b14df0279f06c659d160c9347694905e170ac7
Task-Url: https://github.com/LorenzoBettini/xsemantics/issues/issue/28
28: updated aggregator file

Change-Id: I1028d9c0f856db2b8b45bdb633d27320627863b5
Task-Url: https://github.com/LorenzoBettini/xsemantics/issues/issue/28