Reintroduce git.exe for a hybrid shell approach

This release re-introduces the usage of git.exe to determine branch diversions due to it's speed in doing so. Libgit is still used for other small tasks due to it's speed over shelling out to git.exe.

Improved performance with libgit

Lots of performance improvements, notably the use of the C library libgit which replaces the shell to git commands to git and parsing the text.