Log Message:
Update to 1.0.13:

Changes between version 1.0.9 and 1.0.10

Fix for http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=459763 incorporated,
thanks to Gergely Nagy for contributed code.

Changes between version 1.0.10 and 1.0.11

Support for xz in cdiff, patch by Ville Skyttä; code cleanup from Akim Demaille;
patch to provide custom diff command from Rainer Nagel.  Improved wdiff support
inspired by patch from Peter van Dijk.  Improved debdiff detection.

Changes between version 1.0.11 and 1.0.12

Packaging refactoring and minor packaging fixes.

Changes between version 1.0.12 and 1.0.13

Avoid accidentally identifying some diffs as side-by-side, handling colordiff
arguments better.  Plus code refactoring, corrections to docs.