Changes

Add clearing tool to remove things on chunks/adts inside the cursor radius:
-> terrain height, textures, texture duplicates, texture layers with alpha values below a threshold, texture flags, liquids, M2s, WMOs, shadows, vertex colors, impassible flags and holes
Add some very basic collision detection for models and water in fps camera mode to be able to walk on models and not sink in water
Add liquid layer infos in the details info window ('F8')
Show all liquid layers when selecting a chunk in the details info window ('F8')

Fixes