Save function

**Added save/load function**

When save functionality is enabled:
 * saves/Suspeneded.canvas will be saved every 1000 iterations or when stop button is clicked
 * saves/{100, 200 ... inf}K.canvas will be saved every 100.000 iterations

When load functionality is enabled
 * will start by loading saves/Suspended.canvas

When both enabled this effectively gives you the function to pause execution (as it will be saved on stop and loaded on start!)