#275 Better support for the watch command

[Vesselin Bontchev]

Currently, WinCVS provides easy access through its
menus and buttons only to the "cvs watch add"
command. Feature requests:

1) Add support for the "cvs watch on" command.

2) Support finer granularity for the "cvs watch add"
command, allowing the user to specify which operation
(s) - edit, unedit, commit - are to be watched, instead
of always watching all of them.