Highlight Colors

A super popular type of plugin I see for Atom and Sublime is one that highlights recognized colors (like hex and rgba formatted colors in CSS, for example). This can help visualize what color is being specified without having to open up an external tool.

I'd imagine we could set the background color of the string to the interpreted color, calculating and setting a contrasting foreground.

I do something similar in Palette:

https://github.com/cassidyjames/palette/blob/eed9ffa65df13eeac38bf12298fd4c716174973d/src/Widgets/ColorButton.vala#L68-L123

---
Want to back this issue? **[Post a bounty on it!](https://www.bountysource.com/issues/59092943-highlight-colors?utm_campaign=plugin&utm_content=tracker%2F61917289&utm_medium=issues&utm_source=github)** We accept bounties via [Bountysource](https://www.bountysource.com/?utm_campaign=plugin&utm_content=tracker%2F61917289&utm_medium=issues&utm_source=github).