Increased the max hex value to prevent crashing when fully zoomed out and placing organelles.
Implemented undo/redo-feature for MicrobeEditor

Using a closure-based action-command pattern, the MicrobeEditor now internally maintains a list of all changes that can be un- and redone if possible.

- every organelle action as well as creating a new microbe can be un- and redone

- entering the microbe editor and loading a microbe reset the action history

- Since the GUI is being overhauled atm, the implementation is purely code-based and can be used with Ctrl+U for undo and Ctrl+R for redo (because Z and Y are swapped between general European and other keyboard standards, using them has been avoided to prevent confusion until a more compatible solution is implemented)

- To perform an action with undo/redo-support, use the enqueueAction() function and provide it with a table that has an undo() and a redo() function (and optionally, a (MP) cost member).