Merge branch 'jc/thin' into next

Merge branch 'jc/thin' into next

* jc/thin:
  git-push: make --thin pack transfer the default.
  gitk: Fix two bugs reported by users
  gitk: Improve appearance of first child links
  gitk: Make downward-pointing arrows end in vertical line segment
  gitk: Don't change cursor at end of layout if find in progress
  gitk: Make commitdata an array rather than a list
  gitk: Fix display of diff lines beginning with --- or +++
  [PATCH] gitk: Make error_popup react to Return
  gitk: Fix a bug in drawing the selected line as a thick line
  gitk: Further speedups
  gitk: Various speed improvements
  gitk: Fix Update menu item
  gitk: Fix clicks on arrows on line ends
  gitk: New improved gitk
  contrib/git-svn: stabilize memory usage for big fetches