[PATCH] better msw selection support

I've generalised the selection support a lot more so that enabling and disabling of the menu items works amongst other things. msw selection now more closely emulates x selection (from an XEmacs perspective). andy 1998-04-29 Andy Piper <andyp(a)parallax.co.uk&gt; * mouse.el: move x-selection-owner-p type things to selection-owner-p. * msw-init.el: copy zmacs stuff from x-init.el * msw-select.el (mswindows-own-selection) (mswindows-disown-selection) (mswindows-selection-owner-p): new functions. Very simple minded implementation of selectio ownership. * select.el (own-selection) (disown-selection) (activate-region-as-selection) (select-make-extent-for-selection) (valid-simple-selection-p): functions moved from x-select.el for generalized selection. * x-select.el: see select.el changes. * x-toolbar.el: use new selection functions.