Proposed version number change for 21.2

I would like to drop the beta designation as it currently exists and change the version to a triplet -- 21.2.XX. I am undecided whether the string `beta' should remain in the version string. This proposal is biased towards the side of minimal change. In terms of programmer visible changes, the variable `emacs-version' would change from: "21.2 \"Aglaia-pre1\" XEmacs Lucid (beta3)" to: "21.2.3 \"Aglaia-pre1\" XEmacs Lucid (beta)" with the " (beta)" disappearing when the release is imminent. The function `emacs-version' which currently returns (something like) "XEmacs 21.2 \"Aglaia-pre1\" [Lucid] (i586-pc-linux, Mule) of Tue Sep 29 1998 on altair.xemacs.org" would now return: "XEmacs 21.2.3 \"Aglaia-pre1\" [Lucid] (i586-pc-linux, Mule) of Tue Sep 29 1998 on altair.xemacs.org" The variable `emacs-beta-version' gets obsoleted and becomes `emacs-build-version' and the variable `xemacs-betaname' continues as a boolean test whether or not the running XEmacs is experimental or not. This resolves the obvious naming problems when we need multiple post-beta releases prior to 'net release and eliminates the problem of consecutive numbering when shifting from -betaXX to -pre1. If there aren't any serious objections, I'll make a patch which implements this for 21.2.3. Comments?