[PATCH 0 of 6] Updated Gettext infrastructure

[Martin Geisler]

Hi everybody,

This is an updated version of the patches for enabling translations of
Mercurial:

* Patch 1 restructures the helptable so that the header can be
  translated nicely in the next patch.

  Changes since last time: I forgot to update doc/gendoc.py, that is
  now fixed.

* Patch 2 marks strings in helptable for translation and runs
  extension docstrings through gettext.

* Patch 3 is new, it makes gendoc.py use gettext as appropriate
  instead of _. This fixes some pygettext.py warnings.

* Patch 4 is also new. It tries to fix the way the record extension
  mixes docstrings with prompts and user input.

* Patch 5 makes it easier to find the hg.mo files. The gettext module
  would lookup the hg.mo file corresponding to xx.po in

    /usr/share/locale/xx/LC_MESSAGES/hg.mo

  But that makes it annoying to test new translations and difficult
  for people who does not install to that location. So I changed
  i18n.py to use a path of . or .., relative to the location of
  i18n.py. This is the same way templater.py uses to find the
  templates directory.

* Patch 6 adds new targets to the Makefile for updating the hg.pot (PO
  template) file and to generate xx.mo files.

  Changes since last time: the MANIFEST target makes sure to include
  the hg.mo files, and the extraction of docstrings is more precise.
  Docstrings are now extracted from:

    mercurial/commands.py
    hgext/*.py
    hgext/*/__init__.py

  which I hope catches everything we want. It still finds too many
  strings, but I think it is okay to adjust this along the way.

The test suite still passes after these changes! :-)