Lock management

[mastercoms]

PBSync can automatically set read-only for unlocked files, unlock unchanged assets, and lock changed ones, as Git LFS in conjunction with UE4 Ed can get stuck in invalid states sometimes.

[mastercoms]

Read only functionality done in 7f4fb9e

[commodo]

does this require anything else to be closed?

[mastercoms]

Yes, it should unlock assets if they are up to date or behind all of the 3 main branches: master, promoted, and trunk.

[mastercoms]

Also it may be better to use the git-lfs executable within the UE4GitPlugin (engine_dir/Engine/Plugins/ProjectBorealis/UE4GitPlugin/git-lfs.exe), since that supports multi-threaded lock/unlock.