remove debugging output
beef up StructureParserTests with some passing tests

adding them since they're going to fail once merged to master;
it's #414
Merge remote-tracking branch 'origin/5.0.x'

Conflicts:
	src/test/org/nlogo/compiler/StructureParserTests.scala
	src/test/org/nlogo/headless/TreeAgentSetTests.scala
fix StructureParser regression (fixes #414)
Merge remote-tracking branch 'origin/master' into core