update combat ai behaviour; more variety

3 stages of combat (for AI): 
far away pathgrid following
close-up when shortcutting right to player (and in the end can start attack)
melee when using kind of tactic with dodging and different kinds of attack types (no combos:( )
Added case for distant combatants(archers, throwers)

Almost all behaviour depends on reaction (mTimerReact) updates period (pathfinding is here, too)
Also path now rebuilds only when target has moved on some threshold distance