Dust and enhance

[teamcons]

• Change deprecated tags in Metainfo and also make the app a little more discoverable (cough cough I also added my app in suggests cough cough)
• Change the Readme mostly to fix the icon not displaying (i previously moved icons around to respect modern conventions)
• Add a bit more space for the checkbox labels, to accommodate for longer languages (uneven sliders are ugli)

Draft because at work. Want to test the new sizes, that this builds, and make the code a bit prettier

[teamcons]

I swear you're going to start having nightmares about this girl nagging you constantly for an app that is like three sliders in a Gtk.Trenchcoat, but im german enough to make it everyone's problem
(Ok but honestly after this PR im done)

[dar5hak]

But now I like nagging Germans 🥺 I mean I have Rammstein, but they don't nag me enough.