advisor nodes for xtext 2.4.3

Change-Id: I765e1b370dd0b7e78487e753bfae12cecfd9a937
[Issue 10] check for null in computeType(EnvironmentAccess) 

https://github.com/LorenzoBettini/xsemantics/issues/issue/10

Conflicts:
	plugins/it.xsemantics.dsl.tests/src/it/xsemantics/dsl/tests/XsemanticsParserTest.xtend

Change-Id: Ic8e22c88d5f72309e6684612cd751a9759612063
incremented version 1.3.5

Change-Id: I22fc34ea2cfaebb77bc0f83acea68622cc93e774