[Skyrim] Collisions not fully implemented for TREE/FLOR

• In the case of big trees, only tree trunks should be collidable.
• Harvestable flora like Mountain Flower shouldn't have collisions at all

A good place to test this is coc riverwood

P.S. Thank you for your amazing TES4 support! This is already impressive.

If anyone already knows particular nif tag, please leave a comment here.