orx-kinect refactoring + new general orx-depth-camera (#257)

orx-fx/README.md

@@ -167,6 +167,25 @@ fun main() = application {
 }
 ```
 
+### Colormap
+
+Colormap filters operate only on the RED color channel. For example
+depth maps from
+[orx-depth-camera](https://github.com/openrndr/orx/tree/master/orx-depth-camera).
+
+They allow selection of `min` / `max` value range and applying exponential
+shaping `curve` within this range:
+
+- `GrayscaleColormap` - maps to gray tones
+- `SpectralZucconiColormap` - maps to natural light dispersion spectrum as described
+  by Alan Zucconi in the
+  [Improving the Rainbow](https://www.alanzucconi.com/2017/07/15/improving-the-rainbow/)
+  article.
+- `TurboColormap` - maps to Turbo Colormap according to
+  [Turbo, An Improved Rainbow Colormap for Visualization](https://ai.googleblog.com/2019/08/turbo-improved-rainbow-colormap-for.html)
+  by Google.
+
+
 
 <!-- __demos__ >
 # Demos