Removed some temporary case-check error messages.

- Top level commands (function, warp, shop, cashshop, script, trader,
  duplicate, monster, boss_monster, mapflag) will no longer show a
  custom error message when they are incorrectly capitalized.
- Note: This does not mean that the commands are no longer
  case-sensitive. This only means that no special message will be shown
  in case such an error is detected. The script engine will throw a
  normal error, as it would with any other kind of typo, rather than
  treating this as a special case. Enough time was given to update third
  party scripts, and it is now time to clean up our parsing code and get
  rid of these special warnings.

Signed-off-by: Haru <haru@dotalux.com>