Add order-disorder solid solution test, fixed 0K solid solution behaviour
Fix example seismic so that the depth list works
Merge pull request #82 from ian-r-rose/fix_example_seismic

Fix example seismic so that the depth list works
Merge pull request #81 from bobmyhill/add_solidsolution_test

Add order-disorder solid solution test, fixed 0K solid solution behaviour
molar_fraction to molar_fractions (for consistency)
Added site fraction test