Fixed docstring indentation and formatting.
Added some more detail to Config docstring.
Improved DataSet docstrings - added attributes.
Added more detail to Lattice object constructor.
Added clarification and better phrasing to Lattice attribs
Added more detail to the Observable docstring.
Added more detail to the Propagator docstring.
Added more detail to Simulation docstrings.
Removed obsolete code from Simulation object.
Added more detail to TwoPoint docstring.
Renamed common_members as TwoPoint no longer wraps Propagators.
Added loading of constants to core init file.
Added more detail to documentation
Added more detail to TwoPoint documentation.
Updated README to reflect changes to code.
Fixed Simulation run example formatting