General gas calculations

```
calculate_ideal_gas_molarity(pressure, temperature)
calculate_ideal_gas_amount(pressure, temperature, volume)
calculate_gas_solubility(gas, temperature)
```

- pressure
the pressure quantity of the gas

- temperature
temperature quantity

- volume
the volume quantity of the gas

- gas
name of the gas

`calculate_ideal_gas_molarity()`

: calculate the gas phase equivalent concentration of an ideal gas at a specific temperature (i.e. mol of gas / L of volume). Returns a molarity quantity.`calculate_ideal_gas_amount()`

: calculates the amount of an ideal gas at a specific pressure, temperature and volume. Returns an amount quantity.`calculate_gas_solubility()`

: calculates Henry's law solubility constant for a gas at a specific temperature. Henry's law constants are from: Sander, R. Compilation of Henry's law constants (version 4.0) for water as solvent. Atmos Chem Phys 15, 4399–4981 (2015). https://www.atmos-chem-phys.net/15/4399/2015/. Returns a solubility quantity.