v1.03: prestige/upgrade system

This one took waaaaaay more debugging than I expected, but the following changes have been made:

An epilepsy warning has been added for when you first boot the game.
Found and fixed a bug that occurred when starting a fresh game when a saved game already exists.
Tweaked the spawn rate of special effects.
Added a prestige/upgrade system where you can use clicks to buy click multipliers or increase the spawn rate of special effects.
Added four new achievements related to the above.

Please don't hesitate to share feedback and suggestions!

Cursed Clicks,
PotatoWedge