- Updated GetColoursForGreedyPixels to facilitate re-using colours up
to n times, making for much fuller colour pallates.

 - Updated user-notification strings (and timings) to be more helpful
 
 - Moved the big-colour-queue into a generator, at least for ordered
queues, reducing the maximum size of returned colour lists to 2^18
entries. I need to make shuffled queues into a generator too, somehow...