Basic Renderer Configuration

Our renderer instructions are very simple and abstract. For example, to draw a straight line we would use the Forward instruction. The Forward instruction doesn't itself say how far to move. That is instead specified in a separate struct as the step field. Whenever we execute the Forward instruction, step tells us how far to move. Why would these be separate? The answer is that the language we use to describe the L-system has no way to maintain state. The Renderer implementation is responsible for maintaining the state of the current step and angle, but the initial values are specified in the RendererConfig.

The basic RendererConfig struct looks something like:

# #![allow(unused_variables)]
#fn main() {
pub struct RendererConfig {
    pub step: u16,
    pub angle: u16,
}
#}

We'll want a function that takes the configuration as a parameter and returns a new Crab struct that's ready to use.