Remove GitStatus::GetStatusString(), load strings directly

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Mark g_IndexFileMap extern

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Call git_threads_shutdown() after freeing all global variables

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Can disable TGitCache to load/save cache to disk

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Add CacheSave to Advanced Settings

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>
Fix broken build since 9c74b645d02e90716b49f01c77dd4332db116508

Signed-off-by: Sup Yut Sum <ch3cooli@gmail.com>