Water and more

[list] [*] 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 [/list]