update comment
test that `sort` is nondestructive
minor cleanup
test that `sort` doesn't mutate internal agentset order

(passes here, fails in Tortoise)
split core package from api package

and make some initial moves: Syntax, TypeNames, AgentKind.
more to come.
push WorldDimensions down to core package
push Token, TokenType, et al down to core package

and now lex depends only on core not api!
update extension builds for recent changes
Merge pull request #577 from NetLogo/api-package-split

split core package off from api package
eliminate util package in src/main

since util packages are a smell. most stuff moved to api package.
this is a postive advance now that we have a core package which
does not depend on api.

also accomplished by removing some unused code

not sure what to do about src/test/util, so just leaving it for now
Merge pull request #578 from NetLogo/slim-down-util-package

eliminate util package in src/main
publish artifacts as 5.2.0 not 5.1.0

these numbers are somewhat speculative anyway, but at
least for now, builds from master are identified as 5.1.x,
so headless branch builds should be something else
Merge branch 'headless' into scala-2.11

Conflicts:
	src/main/util/Utils.scala
improve source compatibility with Scala 2.11
Merge branch 'headless' into scala-2.11