I18n segmenting tool.

Messages can be segmented into different .po files based on the location
of their occurrences.  This is so Studio strings can go into different
.po files so we can direct Transifex workers to the LMS strings we
really need done.
A few improvements to extract.

Use the configuration more, and we don't need to delete files we're
about to create.
i18n: extract and generate properly handle segments
Ignore fr and ko_KR, so we can play around with them while getting our ducks in a row.