menu code cleanup

* fix some memory leaks
* rename stuff
* fix crash

Removed commands and variables:

  chmenumdl (replaced by menumdl)

  scorefont (replaced by "menufont score mono")

  menuitemvar (better handled with fully dynamic menus)

Changed commands:

  menufont menu font

    Sets the font for a specific menu. If menu is "", the currently
    initialised menu is used. Example: menufont score mono

  menumdl menu mdl anim rotspeed scale

    Assumes the function of the previous chmenumdl. If menu is "", the
    currently initialised menu is used. Specifies, which model to render
    and how. If only menu is specified, no model is rendered.

DOCREF chmenumdl scorefont menufont menumdl menuitemvar

source/src/scoreboard.cpp

@@ -294,7 +294,7 @@ void reorderscorecolumns()
     sscore.addcol(sc_clientnum, "cn");
     sscore.addcol(sc_name, "name");
     copystring(scoreboardtitle, sscore.getcols());
-    menutitle(scoremenu, scoreboardtitle);
+    menutitlemanual(scoremenu, scoreboardtitle);
 }
 
 void renderscores(void *menu, bool init)