Deeper freeze for Emacs-23 branch soon

[Chong Yidong]

If no major problems with the 23.2.93 pretest crop up during the next
week or so, we'll institute a deep freeze for the Emacs-23 branch.

Once this takes effect, commits to that branch should be for regressions
against 23.2, and documentation fixes, only.  All other bugfixes will go
into the trunk.  We'll deal with exceptions, such as crashes, on a
case-by-case basis.

>From now until then, I urge everyone to help with the bugfixing for the
23.3 release.  If you see anything that you think should be a release
blocker, please point it out (and set the severity to "serious" in the
bug tracker).

Thanks!