Added: Contao3 compatibility
Fixed: Tabletree shows even if "change" is not checked
Fixed: No using static Input::post()
Fixed: REQUEST_TOKEN comes now form Contao.request_token
Added: Namespace BackendTableTree
Fixed: Icon from [eval][icon] only used while loading a subtree via ajax
Merge remote-tracking branch 'refs/remotes/origin/contao3-compat'