[AD] 4.2.1 is up, and a version number proposal

[Peter Wang <tjaden@xxxxxxxxxx>]

Hi,

I've uploaded 4.2.1 now.  I'll leave it to other people to announce it
or whatnot :-)


I'm also proposing to institute a fourth version number component.
If there are any "trivial" problems with the 4.2.1 release, then we can
follow up with 4.2.1.1, etc.  Trivial problems are build system bugs,
[major] documentation stuffups, or the problem we had with blit.c and
djgpp in 4.2.0.

Note that the fourth version number component won't be reflected in the
API at compile time or runtime.  Therefore it's only suitable for some
types of fixes, which I guess will be decided on a case by case basis,
if the need should arise.

My reasons are:

- We usually have last minute patches applied without much testing
  before the release.  If one of those patches is bad then a fix won't
  appear in a 4.2.x release until a long time later.

- We could try to make sure all patches receive a decent amount of
  testing before it is included in a release, but that only means
  releases will get delayed even longer.  I think it's pretty clear that
  people will only test something once it's released, so it's
  unrealistic to expect many people to test SVN snapshots.

- Similarly, very few people are willing to test and retest RCs.
  I think it doesn't fit the volunteer model.

- We don't _need_ a fourth version number, but in the 4.2 series we only
  have one number left to work with and there's rather a lot of
  significance attached to it now.  There is a lot of pressure in making
  a 4.2.x release "perfect" the first time around, which drags the
  process out.

Although, I don't actually expect many more 4.2.x releases.

Peter