Gamma corrections and linear contrast adjustment.

code from CanvasComplex.

First version of Primawera

See merge request !10

feat(canvas3d): synchronize other views with the main view.

See merge request xpetrus/primawera-test!9

Since sometimes numpy creates a view instead of copying the data, it was possible to use this behaviour to change the raw data inside the object. I was not able to find the exact condition when this happens as it seems to happen randomly.