Merge branch 'release/1.0.0'

Add a license

Update the readme

Update the changelog

Bump the version to 1.0.0

[Nix] Add gitflow

[app] Adapt the speed to the mode

[app] Use RandomUnicolor instead of RainbowUnicolor for the Unicolor mode

[led_effects::chaser] Introduce RandomUnicolor

[led_effects::chaser] Introduce UnicolorTransition

[led_effects::chaser] Rename OneParameterChaserEnum to ChaserEnum

[led_effects] Introduce a better timing configuration

[led_effects] Extract to its own crate

[led_effects] Enhance the documentation

[gradient] Make gradient_step take the led number as generic