Added options for tweaking some engine perks to the perks ini file

Added some engine function defines & util func for possible later use.

artifacts/mods/gl_npcarmor.ssl

@@ -125,6 +125,7 @@ procedure adjustfid_handler begin
          variable weapAnim := get_sfall_arg bwand 0xF000;
          variable newFid := fid bwand 0xFFFF0FFF bwor weapAnim;
          if art_exists(newFid) then begin
+            set_sfall_arg(0, newFid);
             set_sfall_return(newFid);
          end else begin
             debug_msg("Error: NPC Armor mod: missing FID.");