Water and more

Water (plots, paths, bridges and objects)
Loading error fixed (even broken old projects should be able to be loaded again now)
Loading error message instead of freezing the editor
Settings: added the option "Alternative Camera Process" (If you have problems with camera control, try this option)
Fixed ctrl z/y for undo/redo
Towers of walls are now rotatable afterwards
You can now switch to the next object by key
Stronger drawn roads
Minor adjustments and bugfixes