Fix inconsistencies in guest nick name generation
When the setting net/nick is empty, HW generates a guest name. But there were several problems:
- Team name did not match guest name
- Random guest number was re-rolled multiple times, causing inconsistencies
- Guest number was often too large (now capped at 99999)
# physfs-rs [](https://travis-ci.org/PistonDevelopers/physfs-rs)
## Rust bindings for PhysFS
This project is built against the Rust nightly and PhysFS 2.0.3
[How to contribute](https://github.com/PistonDevelopers/piston/blob/master/CONTRIBUTING.md)