"No backends available" if colour cannot be imported

[xgqt]

While packaging Polychromatic for Gentoo I stumpled upon this weird interaction:
if colour cannot be imported Polychromatic will claim there are no backends available.

It is a very confusing interaction but not a critical bug.

[lah7]

The technical reason is that the colour library is used in polychromatic.fx, which is only imported when importing polychromatic.backends.openrazer. polychromatic.fx is used for manipulating colours for software effects.

It's sort of a bug but also sort of by design. 🤔 The program tries to gracefully import our backends.openrazer module, and assumes OpenRazer is missing when openrazer.client is unimportable. Other dependencies are caught in that assumption if they can't be imported (like colour).

I'll bear this in mind as I have some thoughts to improve the "integration" handling at some point.