Allow garrisoned entities to transform into one that cannot garrison.

[Freagarach]

Currently, when an entity that is garrisoned transforms (upgrades/promotes) into an entity that cannot garrison the formerly garrisoned holder, several things go wrong.

• The garrison flag is not updated (should be done in eject, not perform eject. (Simple)
• The entity that was transformed disappears. This is because first the position of the transforming entity is used to set on the newly created entity -- Garrisoned, thus out of world. Only thereafter a message is sent to the GarrisonHolder to ungarrison (the transforming entity gets ejected and thus receives a position InWorld) and to garrison the new entity if possible (which it is not). Hence the new entity has a position out of world and can thus not be selected nor seen by the player.