Add recipe for abc-mode
Merge remote-tracking branch 'upstream/master'
Fix typo in documentation
Merge remote-tracking branch 'upstream/master'
Fix whitespace
Add directive for building the info file in mmm-mode recipe

Notice that a workaround was implemented for avoiding the version.texi
being locally changed by the build process.  It would be better to
have this fixed by the upstream authors of mmm-mode.  By thye way, I
have already reported this problem upstream, see
https://github.com/purcell/mmm-mode/issues/41
Merge pull request #2042 from rlaboiss/mmm-recipe-build-info

Add directive for building the info file in mmm-mode recipe