Fixed fugacity calculation to account for Pressure etc.
Added Patm as input argument in documentation file
Replaced missing lines that were deleted by mistake in last update to carb.Rd
Added Patm to output data frame
Added Patm as argument to buffer.R
squared '(1-x2)' term if fugacity coeff, consistent with f2pCO2.R and p2fCO2.R and Weiss (1974)
Merge pull request #1 from jamesorr/fugfac

squared '(1-x2)' term in fugacity coeff, consistent with f2pCO2.R and p2...
Merge branch 'fugfac'