have api.Resource use scala.io.Source

no need to roll our own here -- old code dates back to Java days
give methods in api.Resource more reasonable names
Merge branch 'headless' into widgets

Conflicts:
	src/main/api/ModelReader.scala
	src/main/api/Version.scala
	src/main/headless/Shell.scala
	src/test/api/ModelReaderTests.scala
	src/test/headless/lang/Finder.scala