Extended script constants to support NPC sprite IDs

- Added support for constants whose name begins with a number.
- Follow-up to 124ab2a1cdb344f24170a4d91f7000ebabf39b40.
- Replaced calls to setnpcdisplay with hardcoded numeric IDs to
  constants.
- Thanks to Yommy.

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