Makefile: temporary copy of hg.pot is hg.pot.tmp instead of hg.pot~ The file ending of temporary files for generating XX.po has been changed to .tmp (from ~). Use the same ending when generating hg.pot.

Makefile: fix po file updating by using same file name everywhere The update is done on a temporary file since ce5d711475a3. The name of this file was first XX.po~ and has been changed to XX.po.tmp in all except of one place. Do this now.

mq: prefer a loop to a double-for list comprehension The [x for y in l for x in y] syntax is nigh-incomprehensible, and this is a particularly easy case to expand into a loop since there's no 'if' condition in the list comprehension.