* Remove difflib's quick_ratio() call, from quick tests looks it is four times slower than ratio(), and yet it gives the same results...
* Moved code to find all po's in a dir into its own func (will be used by i18n addon tools too).
Also workaround a nasty bug, where unregistered py classes remain listed in relevant __subclasses__() calls, which would lead to crash with python addons i18n tools (main translation was not affected, as messages extracting tools are executed in a brand new "factory startup" Blender ;) ).
Notes:
* Everything is still a bit raw and sometimes hackish.
* Not every feature implemented yet.
* A bunch of cleanup is still needed.
* Doc needs to be updated too!
* handle nicely multiple empty lines in po files (still have to figure out why po writer sometime output two lines instead of one!)
* fix rtl processing!
Notes:
* Most tools here have been updated, only a few (unused :p ) features should be missing. But some updates are rough for now, and performances are globally worse currently, will address this later (this is only really noticeable when you work over the whole repo, anyway ;) ).
* This update breaks "edit translations" addon, will fix it later, once core (i.e. this module) is considered stable again!
