beef up StructureParser testing

add test case for issue #446
Merge remote-tracking branch 'origin/master' into core
Merge remote-tracking branch 'origin/core' into headless

Conflicts:
	src/test/org/nlogo/compile/front/StructureParserTests.scala
latest models
some changes to workspace stuff for Tortoise

WidgetParser is now separate from HeadlessModelOpener, since
the Tortoise docking tests want to use it

Evaluator now exposes a CompilerFlags var for Tortoise
Merge remote-tracking branch 'origin/headless' into tortoise