First stable release

First stable implementation of model for public release.

Initial commit, working towards a stable release.

This is a fairly functional implementation of the model, but we need to make the following changes before it is finalised:

• Introduce non-ideal solvent activities to the solutions
• Add support for jets.
• Allow user to change body forces (i.e. gravity).
• Add option for an efflorescence termination threshold, i.e. when supersaturation exceeds a threshold (default to 2 for ionic solvents).