Prefer the qLib color theme for node coloring, based on type

[johnnyquest]

[gadfly16]

Is the qLib Color Theme documented somewhere?

[johnnyquest]

That's how you turn it on.

Right now about the only concept is "visualizer type nodes are blue", which also includes any built in node with the node type matching the pattern *visualiz* (or something like that). Ah, and Cache SOP is black, Object Merge is green (the idea is that "fetch" type nodes should be green, but it's a wip), that's about it.

@gadfly16 also, I'm not planning to remove the auto-coloring of certain qLib nodes yet (so visualizers still be blue even if this theme is not used). I also don't want to introduce too many other colors, it's a "controversial subject" (==bloody endless and pointless discussion).

(A color theme doesn't change the actual colors on specific nodes, but you can use it to set default colors based on node typename criteria -- you can override it if you assign a specific color to a node).