improve tabline performance during scroll (#362).
Hide hunks when Git Gutter is enabled, but current file is NOT under git version control
Merge pull request #364 from dmitrykruglov/master

Hide hunks when Git Gutter is enabled, but current file is NOT under git...
expose cleaner api to determine empty head.
fix possibility of the branch extension being unavailable. resolves #366.
Correct quickfix window detection pattern
Merge pull request #375 from qstrahl/master

Correct quickfix window detection pattern