po: reorder nearly all of the module code

po: reorder nearly all of the module code

It has grown up incrementally and new helper functions were added right in the
middle of the hooks, most often near the place they were used, which is
practical when doing initial development, but quite ugly afterwards, when helper
functions are useful to separate logic and implementation details.

Today's refactoring commits have brought the code to a much more maintainable
state, IMHO.

Signed-off-by: intrigeri <intrigeri@boum.org>