Fix for AncillaryTick + Bugfix/enhancements/flow

[Aherys]

Please merge and considere previous PR before merging this one if accepted Fix for Issue : #65

• Changed default start point from BeginAbility to PreBeginAbility, allow a better flow when overriding in c++.
• Check are now done in PreBeginAbility
• Fix: GetActiveAbilityCount was also counting ended ability
• Adding check to execute end ability only one time (in case EndAbility is re-called externally or internally)
• Moving GetWorld() of ability from private to protected, cause no reason to be in private.
• Moving Some logic in better places.
• Added some log for VeryVerbose.

[petegilb]

closing in favor of #72