Source port icon, splash screen / branding

[noctonca]

We should display a community art driven splash screen on game load instead of the other distributors. This indicates to the user some branding that this is a source port. The Adeline had some some config for distributors -- see MENU.md

[noctonca]

#92 will make some of this easier to manage. The icon will be important for the release binaries.

I am unsure about community splash screen. I did a poc for it in #93 and it can be done. Just not sure if we should do it.