Add Nix flake

[nilp0inter]

• This PR adds a flake with a derivation using the current nixpkgs's Nim infrastructure.
• The previous nix code is unchanged.
• A small documentation section is added to the README.

[nilp0inter]

Ping @Lord-Valen

[leana8959]

Hello,

I have tried to use the executable built using the nix flake proposed by this PR, however it gives an error "No appropriate visual found", is this related to a bad build process, or am I using the program incorrectly?

[~] $ result/bin/boomer
/home/leana/.config/boomer/config doesn't exist. Using default values.
Using config: (min_scale: 0.01, scroll_speed: 1.5, drag_friction: 6.0, scale_friction: 4.0)
Screen rate: 60
GLX version 1.4
GLX extension:
No appropriate visual found

Thanks :)

[nilp0inter]

@leana8959,

During this year, nixpkgs's Nim machinery changed quite a bit. I updated and simplified this PR, taking advantage of the new function buildNimPackage and now it should work just fine.

Try running:

nix run github:nilp0inter/boomer

Cheers,
Roberto

[leana8959]

I confirm that this version of the flake does work, thank you!

Have a nice day :)