Allow a task type know its own options scope.
Review Request #1095 — Created Sept. 30, 2014 and submitted
|jsirois, patricklaw, zundel|
E.g., JavaCompile should know that its options are under compile.java.
Also fix some stale comments from the goal->task terminology change.
Ran all the tests. Tested that this works when registering options in the new style (will be sent for review in a future change).