Added
- Documentation page for pressure function `patm`
- Gas mixture class `GasMixture`
- Store gas viscosity coefficients to improve performance
Changed
- Moved CAS input parameter to class init
- Rename `Gas.mu` to `Gas.viscosity`, `Gas.k` to `Gas.thermal_conductivity`, `Gas.cp` to `Gas.heat_capacity`, and `Gas.rho` to `Gas.density`