BurnMan v0.9.0

• major documentation overhaul
• new tutorials
• huge performance improvements by caching property values
• python 3 compatibility
• gibbs free energy computation
• new SolidSolution class
• added ideal, symmetric, asymmetric and subregular solution model
  formulations
• computation of chemical potentials
• updated ipython notebooks
• new seismic models
• added EoS fitting functions
• using jit compilation if available
• additional equations of state: Vinet, BM4, ...
• a large number of new minerals in the databases
• much better test coverage

Online documentation: https://burnman.org/doc-0.9.0/