DMP now on GitHub

[fra...@google.com]

The Diff Match Patch project went into hibernation a few years ago when code.google.com shutdown.  Due to work on other projects, DMP fell off the radar for a while.  But we're back now!  The new location for this library is:

  https://github.com/google/diff-match-patch

All the languages (except C++) have been updated.  In some cases (Dart in particular) the language had evolved considerably during our hiatus.  The documentation has been greatly expanded too.

Happy diffing!