Linux & BSD support

[Be-ing]

This is #4 squashed and with a few small commits split out, plus updating README.md, formatting changes, and fixing a few clippy warnings.

[Be-ing]

Unfortunately it seems the KDE method is not really working. I suggest we change to the same method as KDE's implementation of the XDG Desktop Portal by reading the BackgroundNormal key under Colors:Window in $XDG_CONFIG_DIR/kdeglobals and calculating the grayscale value of that color.

[edfloreshz]

Alright, I'll get on that next 👍

[Be-ing]

Maybe serde_ini could help? I'm not sure.

[Be-ing]

The calculation of the grayscale value with qGray is simply (r * 11 + g * 16 + b * 5)/32.

[edfloreshz]

Done, could you test it before we merge @Be-ing?

[frewsxcv]

I just enabled GitHub Actions for CI. Mentioning in case you want to merge/rebase to pick that up here

[edfloreshz]

After @Be-ing's approval, we'll be ready for merge @frewsxcv, should we merge or rebase?

[frewsxcv]

I have no preference between rebasing/merging/squashing. Do whatever you'd like!

[edfloreshz]

Closes #1

[Be-ing]

I tested this on KDE Plasma 5.23.4 on Fedora 34 switching between several color schemes and it works! Great job!

[edfloreshz]

Awesome! Great job as well @Be-ing and @frewsxcv, cheers 🥂

[edfloreshz]

By the way, I've been improving the code, looks way better.

I'll try to upload the commit tonight so you can review it in the morning. unless you're a night owl 🦉

[Be-ing]

@frewsxcv shall we make a new release now that this is merged?

[edfloreshz]

How about we wait until we have #10 ready?

[Be-ing]

10 may take some time to polish and implement on all platforms. I don't think we need to hold back a release for that. Version numbers are cheap. :)

[edfloreshz]

Alright then! 👍🏼

[frewsxcv]

0.2.0 released!