Add Buildings and Trees to Tiberian Sun


Converted with my rudimentary TS-Asset Converter... i would like to add the assets to the INGAME MAP EDITOR BRANCH. So that we have the most in there...

things are missing:
- Rocks (comes also later)
- Veins (hole is in trees.yaml and will be together with Rocks in misc.yaml later)
- UfO is ommented out because the Ingame MapEditor blows up =( ....

to disable all Civilian Buildings in SP mode, set Owner to "None" in default.yaml ... ;) 
Please don't revert https://github.com/OpenRA/OpenRA/pull/6912.