Problem: Extending sign and foldcolumn below the text is confusing.
Solution: Let the sign and foldcolumn stop at the last text line, just like
the line number column. Also stop the command line window leader.
(Christian Brabandt, closes#3964)
Problem: Using an external diff program is slow and inflexible.
Solution: Include the xdiff library. (Christian Brabandt, closes#2732)
Use it by default.