bug#11153: change automake branching policy: dispensing with the 'branch-X.Y' branches in the future

[Stefano Lattarini]

I've now implemented the proposed branching setup, with the following steps:

 - I have removed the old and outdated 'next' branch (which was an
   ancestor of the current 'master').

 - I have removed the 'branch-1.11' branch (whose tip pointed at
   the commit tagged by tag 'v1.11.5').

 - Now that 1.12 is out, I've merged master into maint (with a non
   fast-forward merge to keep this action visible in git history);

 - I have updated the version number in maint to 1.12.0a;

 - I have merged this new maint into master;

 - Finally, I have updated the version number in master to 1.12a.

I'm thus closing this bug report.  Let's hope the new policy will work
out for the best!

Thanks,
  Stefano