[RFC] Renaming and rebasing experimental/rewindable branches

[Stefano Lattarini]

Hello automakers.

I intend to perform the following renames on some automake branches:

 - testsuite-saner-shell => experimental/testsuite-saner-shell
 - aclocal-search-path => experimental/aclocal-search-path
 - automake-ng => experimental/automake-ng

to make it manifest that these branches are still in an experimental
status, and can be rewinded.  I then intend to rebase those branches
on latest master.

I will procced with this plan in 72 hours or so if there is no objection
by then.

Regards,
  Stefano