GDP and translations

[John Mandereau]

Hello translators,

There are some doc sections you can start updating:
- doc PO (don't translate titles named "* sections" or "* FIXME" or
"TODO blah", they are temporary).
- documentation index (index.html.in)
- user/*.tely (NOT .itely files)

Those updates are nitpicks, but this will make translated docs a bit
more usable.  If there are still titles in English in the PDF after
that, update the corresponding section titles in the .itely's.

To run check-translation on a single file, read TRANSLATION... or do
(from Documentation)

python ../buildscripts/check_translation.py ../buildscripts/ lang/foo/bar.baz


The tutorial, Pitches and Rhythms are almost finished, but IMHO it's
better you wait they're really finished before working on them.

Besides this, I had already moved many sections in translated docs, but
some other sections have been moved in the English docs after that; you
can move these in the translated docs too, but beware they have been
revised or will be revised soon, so don't update them now and don't rely
on the COMMITTISH when you update them later.

Cheers,
John