Just more example to experiment with various things

When an entity dies, it is immediately removed from the current selection
Only select entities that can be selected

Create the Task class, which is a thing an entity does, as a single action.
A work can be composed of one or more Task.

Implement AttackTask and AttackWork

uint to unsigned int, and some minor indent

It is used to attach certain response (for example graphical or sound
effects) with various events of the World

With an Acquisition range. Can only target an area and attack encountered
units, since FollowWork is not yet implemented

See http://dota2.gamepedia.com/Cast_animation for details on how this works,
for the gameplay

We use a PathWork to move towards the destination, until the distance is
equal (or lower) to the cast distance.