options screen

i've added an Options screen, where you can

• turn speedrun mode on/off. in speedrun mode, the tutorial is disabled and there's a timer at the top right of the screen.
• change level loading animation speed to 'fast' or 'slow'
• choose between 'classic' and 'modern' controls. with 'classic' controls, Alt jumps/flies and Ctrl drills. with 'modern' controls, Z and X do so respectively.

that is all for now, here's hoping these options enhance your enjoyment.