fix github issue #193 - curses: menu search

Fixes #193

Under curses interface, make characters which are both entry selectors
and menu commands function as a selector.  Needed to support using ':'
to look inside a container when applying/looting it via menu, instead
of performing a menu search operation.  (There was another case like
this but I can't remember what the circumstances are.  The fix is
general enough to cover it, whatever it is.)

For menus which don't have ':' as a choice, make sure search prompt
doesn't offer garbage default input when built with EDIT_GETLIN.

Bug?  If player has 'popup_dialog' option On, EDIT_GETLIN is ignored.
Plain curses I/O doesn't seem to offer a way to implement it.

win/curses/cursmain.c

@@ -202,6 +202,7 @@ curses_player_selection()
 void
 curses_askname()
 {
+    plname[0] = '\0';
     curses_line_input_dialog("Who are you?", plname, PL_NSIZ);
 }