Fix issue where Musicxml2ly generates improper code for minor chords

Fix issue where Musicxml2ly generates improper code for minor chords

The solutions for the invalid combinations
are provided in python/musicexp.py.
A colon is added if a colon-less chord
(i.e., major) has modifications. Adding
additions checks for a trailing digit,
if none, the leading period is omitted.

Note that the changes in python/musicexp.py
are harmless to an un-patched scripts/musicxml2ly.

Doc: update toplevel-score-handler definition reference

The file where the default handler is defined has changed.

Merge branch 'master' into translation


Doc: fix bad xref mentionned in snippets.bigtexi.log


Web-ja: fix links


Merge branch 'master' into translation


Doc-fr: NR-input


web-fr: updates for new front page


Web-ja: update translation


Issue 4969: Update texinfo.tex from upstream

texinfo.tex ver. 2016-09-17.16
It is newer than Texinfo-6.3's.

Issue 4972: Make music-filter more conservative

Deleting music when its 'elements field becomes null? led
to repeat chords disappearing when articulations were
removed.