Changed battle_config definition to extern to avoid mistakes in plugins

- This avoids plugins incorrectly using battle_config (with unreliable
  results) instead of using the proper interface, battle->bc.
- Edited various #defines to use battle->bc instead of battle_config so
  that they can work perperly in plugins as well.

Signed-off-by: Haru <haru@dotalux.com>
Follow-up to b6b3f58795288701d0e162d43fa6f0a47af913b3

- Includes in some files weren't sorted alphabetically. Special thanks
  to KeiKun.

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