Display MainGame.mnu and map in ordoor simultaneously

It's a complete mess for now - many things are out of place or shown
when they shouldn't be - and we can't move around the game map. But,
it's a good start.

internal/ui/noninteractive.go

@@ -16,7 +16,7 @@ const (
 )
 
 func init() {
-	registerBuilder(menus.TypeStatic, noChildren(registerStatic))
+	registerBuilder(menus.TypeStatic, registerStatic) // MainGame has a hypertext child
 	registerBuilder(menus.TypeHypertext, noChildren(registerHypertext))
 	registerBuilder(menus.TypeOverlay, noChildren(registerOverlay))
 	registerBuilder(menus.TypeAnimationSample, noChildren(registerAnimation))
@@ -58,9 +58,9 @@ type animationHover struct {
 	closing bool
 }
 
-func registerStatic(d *Driver, r *menus.Record) error {
+func registerStatic(d *Driver, r *menus.Record) ([]*menus.Record, error) {
 	_, err := registerNoninteractive(d, r)
-	return err
+	return r.Children, err
 }
 
 func registerNoninteractive(d *Driver, r *menus.Record) (*noninteractive, error) {