enhancement suggestions from upstream

[7yl4r]

I wanted to make a list of targeted enhancement ideas from our upstream repo and wasn't sure where to put it so... here it is, roughly in order of priority:

Dev QoL:

• separate core & app code

For fun:

• pickups
• glider shooting / detonation images aka shoot-detonate image #1

player QoL:

• size/detail adjustment to get framerate to 25fps
• custom keybindings / control schemes
• loading screen
• fix +/- buttons on UI

deferred, but still critical later:

• game saving

deferred fun:

• mp