Buffering

This update adds input buffering, faster undo, and accelerating turn speed for those with quick fingers. Resetting a puzzle is now loaded into your undo queue so you can return to your hubris if you restart by accident.

I've added a sine wave to the population of elements in endless mode - the threats and utilities wax and wane out of sync. This makes it less crowded over all and a bit more interesting.

I've also fixed my issues with UI rendering so we're back to the small web demo - this should be less taxing on old computers.

This is all in response to feedback I've received. Thanks to everyone who took the time to respond.