New ancillaries for RC318 and R113 and MethylStearate

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
More testing of ancillary equations

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Fixed Brent for saturation p at low temperature/pressure

Signed-off-by: Ian Bell <ian.h.bell@gmail.com>
Changed methanol critical pressure to be the same as REFPROP

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