swift234

Clean up the command line interface for 'swift'

In the interactive driver, disable a bunch of flags that only work with
swiftc driver (NoInteractiveOption => disallowed, doesn't show up in
help when invoked as 'swift').  Also move some options to HelpHidden
(hidden from -h in both 'swift' and 'swiftc') that we don't need to
advertise.

Swift SVN r20780