Marked command 'cmdothernpc' as deprecated.

- Note: The command will be completely removed after about a month.
  Custom, third party scripts will require updates, in case they were
  using this command. Please see the 'cmdothernpc' documentation.

Signed-off-by: Haru <haru@dotalux.com>
Marked commands 'enablearena' and 'disablearena' as deprecated.

- Note: The commands will be completely removed after about a month.
  Custom, third party scripts will require updates, in case they were
  using these commands. Please see the commands documentation.

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