Convert menu-exec-wm from an abritrary exec menu, into a config-based menu from

which one may configure (wm <name> <path_and_args>) (and choose) specific
window managers to replace the running one. 'wm cwm cwm' is included by
default.

No objections and seems sensible to sthen.

parse.y

@@ -70,7 +70,7 @@ typedef struct {
 
 %token	BINDKEY UNBINDKEY BINDMOUSE UNBINDMOUSE
 %token	FONTNAME STICKY GAP
-%token	AUTOGROUP COMMAND IGNORE
+%token	AUTOGROUP COMMAND IGNORE WM
 %token	YES NO BORDERWIDTH MOVEAMOUNT
 %token	COLOR SNAPDIST
 %token	ACTIVEBORDER INACTIVEBORDER URGENCYBORDER
@@ -146,6 +146,16 @@ main		: FONTNAME STRING		{
 			free($2);
 			free($3);
 		}
+		| WM STRING string	{
+			if (!conf_wm_add(conf, $2, $3)) {
+				yyerror("wm name/path too long");
+				free($2);
+				free($3);
+				YYERROR;
+			}
+			free($2);
+			free($3);
+		}
 		| AUTOGROUP NUMBER STRING	{
 			if ($2 < 0 || $2 > 9) {
 				yyerror("invalid autogroup");
@@ -317,6 +327,7 @@ lookup(char *s)
 		{ "unbind-mouse",	UNBINDMOUSE},
 		{ "ungroupborder",	UNGROUPBORDER},
 		{ "urgencyborder",	URGENCYBORDER},
+		{ "wm",			WM},
 		{ "yes",		YES}
 	};
 	const struct keywords	*p;