Git's patching functionality has been moved to the new Patcher API,

giving us a more future-proof, standardized way of patching, reverting,

and committing.
Patching is still implemented as individual git apply -3 commands, one

per patch, rather than bulk-patching via git am. This is to avoid any

surprises with the patching process, since Git doesn't have any problems

applying patches to dirty trees.
Unit tests were added for all the Git patching logic.

Unit tests pass.
Manually tested applying patches, committing, and reverting.