allow menu checkboxes to change position

and: fix enumsounds, kill some CR, cleanup

menuitemcheckbox <text> <value> <action> <position>

  Now takes an optional fourth parameter "position" in the range from 0
  to 100, default 0, which moves the position of the checkbox over the
  width of a text input or slider, with 100 being left and 0 being right.

DOCREF menuitemcheckbox

source/src/serverms.cpp

@@ -161,7 +161,6 @@ void flushmasterinput()
 }
 
 extern char *global_name;
-extern int interm;
 extern int totalclients;
 
 // send alive signal to masterserver after 40 minutes of uptime and if currently in intermission (so theoretically <= 1 hour)