Clean up option and selection flags.

Clean up option and selection flags.

Rename the enums used for flags such that they are more likely unique.
Also a bit of other clean-up to limit the use of the option flags more
into the generic parts.  Removed a few unnecessary flags.  Made
efClearOnNextSet work more correctly for classes that don't use
OptionStorageTemplate, although currently it didn't cause any issues
(noticed some issues while developing SelectionFileOption, but the final
version worked without these fixes).

Change-Id: I78c243c4f73b87b285eb54d6ff3ae42699678962