Status: Colorize volume icons

[newhoa]

@ochosi, if you could take a quick look at the "colorize volume" and "colorize battery" PRs I'd appreciate it. I'd like to make sure you're okay with continuing the colorization of the status icons.

This is something we talked about a year or two ago a few times (like here). We kind of already started this with coloring the Wifi icons but just wanted to make sure it's still an okay direction.

If developers want symbolic icons, they now have that option in Gtk3+ and Qt5+. If they don't then we should honor their design. Non-symbolic icons being all color gives a more consistent user experience.

Ultimately I think it will lead to being able to get rid of the -dark variant, as icons will be legible in light and dark themes.

Current:

Proposed:

---

Use full color icons for volume. These icons match the rest of the color theme better and are easier
to see in both light and dark themes.

Remove same-named monochromatic icons from the panel folder. Symbolic icons (which automatically recolorize) are now common so these monochromatic icons should no longer be needed. In places where developers have chosen not to use symbolic icons, we shouldn't force the look. This also solves an issue where the monochromatic icons were difficult to see with mixed light and dark themes (especially with per-app
light and dark theme preferences becoming more common).

Symlink -panel suffixed icons to the new
colorized icons at 16px, 22px. These still
may be used for ayatana indicators. Not sure
if any sizes other than 22px really needed.

Fixes #416
Fixes #90
Address part of #362
Addresses part of #346
Newer solution to #180

[ochosi]

Agreed, that totally makes sense. Thanks for working this out!