Quest Log system improvement. (Hercules 6f55c00)
- Improved memory usage of the quest log system. (saves up to 75kB per online character).
- Fixed various issues with quest entries disappearing from characters without an apparent reason, or monster kill counters getting stuck - the issues were caused by a de-synchronization between the two parallel questlog arrays in map_session_data.
- Added some code documentation.
- Thanks to @shennetsind and @MishimaHaruna.