Merge Ironhorde Burrow and Tower

[Eagle XI]

Similar to what i had request earlier for the default version. This one will be for Felhorde.
Tower is to become upgrade of Burrow.
Take the Burrow, open its roof, put the tower in it.

 

[Eagle XI]

I really could use this, Ujimasa Hojo gives permission in advance to edit his stuff anyways.