Notificator, training zone hero

- Notificator which allows you to display and notification text for a
given amount of time in seconds.
It uses the first in first out principle.
- Moved the check if a unit can attack another unit to the gamemanager.
Since we maybe need that check in other places to.
- When capturing an trainingzone train the unit to an hero unit. The
hero buffs are not yet applied.