fade node with checkerboard

[malytomas]

Fade node ignores checkerboard connected to the fade factor.

Tested with commit 772a912
Using visual studio 2019. detected avx2

[Auburn]

I think this is because checkerboard returns -1 or 1, and fade is done between 0-1
It might make more sense for fade to use the -1 - 1 range since that is what most noise types output to

[malytomas]

Alternative solution could be to make the checkerboard node take the two values as inputs.
Or perhaps change both the range of the fade and add the inputs.

Either way, I do not have strong opinion for either solution here. I am just bringing ideas.