Splash screen and a main menu

[mbaruh]

Should start with a splash screen, like the pydis logo fading in and out

A main menu. Concept by lemon:

• Should have background music
• Sound when hovering over an option

Bonus point:

• The option slightly grows when you hover over it
• The ducks in the background move. This will be easier to do when we have the game logic down, and might be deferred to a future issue.
• Make the tongue wiggle

[lemonsaurus]

We haven't solved all the bonuses here, but the main points are fixed. Let's move the low priority stuff into another issue.