replace binary io by Parallel netcdf io 
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We can check the io files using ncview now in both prep and main model stage.
Also, redundant io files are removed for clearity.


implement from single precision to double precision
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For slimplicity, implicit real*8 is used.
MPI related info communication and Pnetcdf io are also modified to meet real*8 requirement.


add cfc module
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input files needed in initial step are moved to $model/data/
input files: timcom_gasx.nc, cfc1112_new.atm

To adjust cfc content in different years, see variable: "index" @ subroutine cfcsurf

