Procedural city generation algorithm implemented in Rust/Bevy.

This code is based on citygen-godot project: https://github.com/t-mw/citygen-godot (see also their online demo: https://www.tmwhere.com/city_generation.html).

Which in turn is based on paper "Procedural Modeling of Cities (2001)": https://cgl.ethz.ch/Downloads/Publications/Papers/2001/p_Par01.pdf