Don't throw away a catalog's obsolete messages when you update it
Merge pull request #29 from nickretallack/master

Don't throw away a catalog's obsolete messages when you update it
Added changelog entry
Added an early failure for non existing data
Fixed a broken reference
Removed wiki quick links from the docs because they are not particularly useful
Updated and corrected date docs
Fixed a broken sphinx directive
More documentation cleanup
Fixed a broken reference
Some more documentation updates
Added authors file
License clarification and cleanup
Added basic likely-subtag resolving
Fixed a bug in the subtag resolving
Fixed a missing call to get_timezone
Added a block about LOCALTZ
Renamed a parameter (variation -> variant)