Merge branch 'np/delta' into next

Merge branch 'np/delta' into next

* np/delta:
  diff-delta: allow reusing of the reference buffer index
  diff-delta: bound hash list length to avoid O(m*n) behavior
  diff-delta: produce optimal pack data
  Merge branch 'kh/svnimport'
  Merge branch 'js/refs'
  annotate: fix -S parameter to take a string
  annotate: Add a basic set of test cases.
  annotate: handle \No newline at end of file.
  gitview: Use horizontal scroll bar in the tree view