Minor edits to pc_statusup documentation comments

- Follow-up to a3fecfc

Signed-off-by: Haru <haru@dotalux.com>
Added UTF-8 BOM detection

- This prevents things like the following from happening, by warning the
  user if an incompatible file is loaded:
  http://hercules.ws/board/topic/5126-mapname-selft-announcer/?p=33068
- We're erroring out instead of ignoring it, as explained in the source
  comment.
- Special thanks to jaBote.

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