Revert "use WorldLocation instead of SpellTargetPosition (code simplify)"

This reverts commit 0e1a8f11ffb387f22e221bb8f211881b508b931b.
use WorldLocation instead of SpellTargetPosition (code simplify)
fix compile, thx to Undergarun
use WorldLocation in AreaTrigger operations
use G3D calculation in CanReachWithMeleeAttack