Support multiple collections with different highlight colors

[Maxr1998]

I'd love to be able to separately highlight different collections. I currently use the plugin to highlight all the albums in my physical collection, but it would be useful to also highlight digital releases I collected in another color. This could be solved by offering 2-4 slots where collections could be loaded into, each with different highlight colors.

[jesus2099]

Hello @Maxr1998, I know it's still not possible but I have just fixed something slightly related:

• fix: #822