Customizable script to allow honor from creature kills

* See CONF section: CUSTOM SERVER OPTIONS - CREATURE HONOR
* For existing servers, please import: characters_create_creaturehonor_message.sql
* Made a change to CMakeLists.txt which allows inclusion of custom scripts. Re-run CMake if you're not starting fresh.
All I did was copy it directly from existing 335 code. I hadn't even considered the 6.x branch, honestly.