During the cleanup of the SCM code in RBTools 4, we introduced

rbtools.clients.base.patch, which contained PatchAuthor and

PatchResult classes. In preparation for upcoming patch-related work,

these are moving once again to rbtools.diffs.patches.
The old module will continue to work, but is now marked deprecated. All

call sites have been migrated to the new module.

Unit tests passed, both with and without the import updates.