Added skeleton-auto.css, which dynamically sets the theme based on the browser and/or the Operating Systems colors, if supported.
Set Default Theme to Auto with comments on helping switch to light and dark theme stylesheets.
Darkened the skeleton-dark.css background color to the same as the color that skeleton-auto.css sets it as, which is html recommended standard color of #121212.
Removed a few deprecated brands, including Mixer and Spectrum.
Updated iconography and brand colors to align with guidelines set by brands and to help increase visual accessibility. This will likely be the new style moving forward, so if you want to go back to brand color button backgrounds and solid white or black iconography, you'll need to do that on your own.
Added Facebook Messenger and Vimeo, please keep the suggestions coming for popular services that you believe should be included in the main branch for everyone by default.
Updated .icon padding to make iconography appear centered.
Updated container alignment to center to remove outdated attribute.
Removed underline from links within buttons.
