[addon] Dismantling buildings

[Spikeone]

How it should work:

• player should have two options: to dismantle building (and get some building materials back) or to burn it and get nothing
• when you choose to dismantle building, a builder should slowly dismantle it and get part of the building materials back
• the amount of the building materials which you might get back, should depends on the 'refund materials' option
• the time of dismantling should be equal to the time of constructing each building

How to enable this addon:

• this addon should be optional. Should be available like other RttR addons (in options).

Why this addon:
I was inspired by Widelands game, where the animation of a builder which is deconstructing the building looks very cool and fits in Settlers. Besides it is more realistic.

https://bugs.launchpad.net/s25rttr/+bug/1394125

[Spikeone]

I just read this text and I guess, it would be kinda good if there was this option but not that slow - so you press the dismantle button and then it takes 1/2 of the time a fire would burn and gives you 1/2 of the goods used.