[cvsnt] Latest updates

[Tony Hoyle]

cvsnt 2.0.56 (Release candidate)

Shouldn't be much if anything left wrong with it now.

* Stop various admin options defaulting to HEAD
* Premodule/Postmodule to complement Precommand/Postcommand.
   These only fire on module-based commands (checkout, rtag, etc.)
   not sandbox-based ones (updated, status).
* If the server supports rls then send it in preference - hopefully
   this will make us somewhat compatible with cvs 1.12.
* All known bugs to date.

Tony