Improve handling of TargetMMGen

This will have impact on Chase and Follow Movement.

* Refactor code to check if a new position is required for the MMGen into the new function RequiresNewPosition
* Refactor code to get the current targeted distance into function GetDynamicTargetDistance
* Change ChaseMMGen (angle = 0.0f case) chase to best contact point, not zero angle.

Thanks to Cala and X-Savior for testing. Special thanks to cala for also suggesting improved values for the magic numbers
Close #112