2.3.0

• DefectsThermodynamics class has been added to replace and greatly expand the functionality of the
  DefectPhaseDiagram object. See tutorials for functionality and usage (plotting, Fermi level /
  concentration analysis, dopability, transition levels (with/out metastable etc).
• Overhaul supercell generation as discussed, now optimises directly off minimum periodic image distance
  (thanks to efficient optimisation algorithm) with some prudent constraints. Significantly reduces
  supercell sizes required in most cases.
• Overhaul defect grouping as discussed, to use the distance between equivalent defect sites (with this
  controllable via the dist_tol parameter).
• Add point symmetry and orientational/spin degeneracy parsing, automatically included in thermodynamics
  analysis (and customisable by user).
• Many efficiency improvements (particularly in defect & input file generation, and symmetry functions).
• Check and warning for large defect displacements far from defect site.
• Site displacement (local strain) plotting by @ireaml 🙌
• Auto determination of X-poor/rich facets.
• More control over site selection for eFNV correction.
• Clean, grouped parsing warnings for DefectsParser (in case many warnings...)
• __repr__ methods for all doped classes for informative outputs.
• Tests and tutorials updates.