Remove legacy flag support from new options.
Review Request #1328 - Created Nov. 13, 2014 and submitted
|ity, patricklaw, zundel|
We no longer need it now that we're on the new parser.
Removed a couple of legacy= kwargs, to prove that things still work.
Future changes will clean up the remaining kwargs from option registrations.
Integration and unit tests passed.
Full CI baking.