add release notes

   to a release-0.2.x branch, manually commit the changelogs to the later

   git branches too.

   If you're doing the first stable release in a series, you need to

   create a ReleaseNotes for the series as a whole.  To get started

   there, copy all of the Changelog entries from the series into a new

   file, and run `./scripts/maint/sortChanges.py` on it.  That will

   group them by category.  Then kill every bugfix entry for fixing

   bugs that were introduced within that release series; those aren't

   relevant changes since the last series.  At that point, it's time

   to start sorting and condensing entries.  (Generally, we don't edit the

   text of existing entries, though.)

4. In `maint-0.2.x`, bump the version number in `configure.ac` and run

   `scripts/maint/updateVersions.pl` to update version numbers in other

   places, and commit.  Then merge `maint-0.2.x` into `release-0.2.x`.