Add option to use an exponential scale for the volume slider

[cryeprecision]

Description of the feature:

I'd like to add a feature that introduces a exponential scale for the volume slider.
This issue is mostly for myself so I don't forget about this and I want to submit a PR soon-ish.

Other info / sketches:

This site explains why I want to do this
https://www.dr-lex.be/info-stuff/volumecontrols.html

This repo has an example implementation but I'd rather extend this plugin than install another one
https://github.com/DamienTaubman/youtube-volume

[Sv443]

Alright, thanks a bunch! Just know the develop branch has the new version that's about to be released, so you should base your own branch on that one.

[Sv443]

fyi, I added another feature (in advanced mode), to have the slider label use the exponential value as well.
You can now install the latest dev version with all these changes through the button in this PR.

(& the "initial tab volume" slider will also display it):

[cryeprecision]

Uhh, nice! I was thinking about removing the value in the parenthesis since it might be confusing but adding an option is a better solution

Also thanks for the heads up about the link to the dev version, I missed that :P