Bug Fixes
* Fixed a typo in a define. Thanks to exneval.
* Fixed a potential crash with Ankle Snare. (bugreport:8977)
* Fixed a potential crash with Explosion Spirits SP recovery. (bugreport:8978)
* Cleaned up Fire Expansion - Acid, Varetyr Spear, Kunai, Dark Crow, Counter Slash, Taekwon Kicks, Freezing Trap, Weapon ATK Element bonus, and Force of Vanguard damage formulas.
* Added missing Research Fire Earth VIT bonus.
* Fixed some potential issues with ATK calculations. Follow up to 89ef868's battle calculation cleanup. Thanks to exneval.
* Another follow up to 89ef868 to resolve Extremity Fist sliding effect.
* Various clean-ups.
Merge branch 'rathena/master'