Merge branch 'maint'

* maint: (46 commits)
  git-gui: Changed blame header bar background to match main window
  git-gui: Favor the original annotations over the recent ones
  git-gui: Improve our labeling of blame annotation types
  git-gui: Use three colors for the blame viewer background
  git-gui: Jump to original line in blame viewer
  git-gui: Display both commits in our tooltips
  git-gui: Run blame twice on the same file and display both outputs
  git-gui: Display the "Loading annotation..." message in italic
  git-gui: Rename fields in blame viewer to better descriptions
  git-gui: Label the uncommitted blame history entry
  git-gui: Switch internal blame structure to Tcl lists
  git-gui: Cleanup redundant column management in blame viewer
  git-gui: Better document our blame variables
  git-gui: Remove unused commit_list from blame viewer
  git-gui: Automatically expand the line number column as needed
  git-gui: Make the line number column slightly wider in blame
  git-gui: Use lighter colors in blame view
  git-gui: Remove unnecessary space between columns in blame viewer
  git-gui: Remove the loaded column from the blame viewer
  git-gui: Clip the commit summaries in the blame history menu
  ...