Option to change hoverboard speed

Like increase it 2x, 3x, or even 10x faster, or also slow it down like 0.8x, 0.2x, etc.

[AMDmi3]

Random speed setting is not what I'd expect from the game. Original had 'gandalf mode' though, which makes you jump higher - that would be nice to implement, especially if it's activated after you collect all the coins. Kinda like an achievement from #19.