Skelril Explosion Modifications
Fixed the volume calculation on Polygonal regions
Changed formula

http://www.mathopenref.com/coordpolygonarea2.html
Removed hacky work arounds
Merge branch 'explosion-cfg' into skelril

Conflicts:
	src/main/java/com/sk89q/worldguard/bukkit/WorldGuardEntityListener.java
Implemented a PvM flag