Add examples of selector syntax
Sketch out effect template
Add blinker example
Add character example
Add circle example
Add clock example
Add constant example
Add countdown example and tweak clock a little bit
Add cube example
Add fish example
Add game of life example
Add gradient example
Add heart example
Add ilkka example

Not sure if we are going to need set_z yet so I left that out for now. Maybe
whole set API should operate on floats ([0, 1] instead of [0, leds]).
Add layers example
Add line example
Add lines example
Replace Math with math

It is better to include native math functions into our own module for the sake
of consistency.
Add matrix example
Add particles example