Add more colors to the extension

[Bakkertje01]

Can you please add more colors :)

[pianoskateboard]

And more icons! Waaaaay more!!!

[GarlandKey]

I second this. I've been using this extension since it was first released. Anyone using this extension is going to be a power user. As such, we need to be able to set our own colors or a much larger color palette should be added.

[dannycolin]

This needs to be implemented directly in Firefox. Also, if a solution is implemented upstream, it will definitely be a way to select a custom color so I'm going to close this issue in favor of #391. Please upvote this one. Thanks :)