[Enhancement] Add Color-Picker

[alexshadowolex]

In the Overlay-Settings-Screen, a color picker for every color would be helpful.

Something like this:

Bonus with this would be that all possible color formats can be displayed + a checkbox for transparent.

[1recyclebin1]

I've tried adding a colour picker initially and had issues with properly integrating it into the app and didn't figure how to sort it out. Maybe at some point in the future when I learn more I'll be able to integrate this with proper background and settings.
the text box currently accepts anything from css3 to css5 and the colour box should reflect those changes. (has been the case since #38 )
for invisible you can just write "invisible" in the textbox or even keep the it empty and it would default to that.

[alexshadowolex]

Yeah makes sense. Let's keep this issue then as documentation until you figure it out, it's low prio anyways :)

The other stuff with integrating all possible color formats and transparency was just an idea to improve the color picker. Currently the only info about the available formats (that I found within the first hour of using the app) was the tooltip and that could make it more integrated and easier to use.