Updated saturation spline curves

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

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
More useful error message for critical spline

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

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Remove std::size_t cast in ReducingFunctions

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Changed the cast for benzene higher-order viscosity

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Updated flash routines at low temperature to close https://github.com/CoolProp/CoolProp/issues/124

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Merge branch 'master' of https://github.com/coolprop/coolprop