Polish nodes

[MathemanFlo]

I tried in increase ArmorPaint's usability. This PR implements two things.

1. A new "Replace Color" node. It does exactly what it sounds like

is changed to

by these nodes

The fuzziness is to create softer regions:


made by:

In theory this result could be achieved with a combination of MixRGB and Color Mask but I believe this to be way more intuitive and replacing a color is a relatively frequent operation.

2. I started adding some tooltips to nodes I believe are harder to use. Most are relatively straight forward, but the 'Bump' node isn't for example. Implements: Tooltips for nodes #927 In case you dislike the wording, feel free to give me an example and I'll try to adapt the others. In case you find other hard to use nodes, feel free to list them and I will add further tooltips.