Should at least be in util folder. And since it is imilar functionality 
to the unit factory it is placed within.

This was an early draft and unused. Will be reintroduced in a proper 
form later.

Also some small improvements to variable naming and file structure.

#23

* Only elements which has to be registered by the player's form inherit
from `FormElementComponent`
* Element components use their specific `elementModel`
* Rename file for `FormElementComponent`

Since this does not label anything but instead is meant for (longer)
texts.