ExcessHEFunction.h all unsigned int replaced with std::size_t

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
PhaseEnvelopeData now in CoolProp namespace

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
PhaseEnvelopeData can be extracted using the get_phase_envelope_data function from the AbstractState

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
PhaseEnvelope added to CoolProp.i SWIG interface

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Cleaned up the c_Y functions for GERG to make use of the beta functions relationship beta_ij = 1/beta_ji

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Fixed module finder for windows for octave

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>