bar misuse of task variables (fixes #348)
reformat
clean up imports
Merge remote-tracking branch 'origin/master' into core

Conflicts:
	headless/src/test/org/nlogo/headless/TestErrorMessages.scala
Merge remote-tracking branch 'origin/core' into headless

Conflicts:
	headless/src/main/org/nlogo/parse/LetScoper.scala
	headless/src/main/org/nlogo/parse/StructureParser.scala
	headless/src/test/org/nlogo/parse/LetScoperTests.scala
	src/test/org/nlogo/headless/TestErrorMessages.scala