Implement multiscale Turing patterns

[mikolalysenko]

http://www.jonathanmccabe.com/Cyclic_Symmetric_Multi-Scale_Turing_Patterns.pdf

[rreusser]

Success! Used the fft for two convolutions at a time, but I'm pretty sure I could use the real valued fft to double that up and accomplish four convolutions in a single fft, which would nicely speed things up. Very happy it's not more complicated.

Will further clean up shortly. Maybe color.

Source: https://github.com/rreusser/rreusser.github.io/tree/master/src/src/multiscale-turing-patterns Build (click to randomize): http://rreusser.github.io/multiscale-turing-patterns/