Add output in csv format.
Modification of mass balance output.

- optimization of input types and its reading
- small changes in csv output method
Mass balance output in csv and GnuPlot format.

- modification of output
- format output by delimiter char
- optimization of data header printout
Replace double quotes in strings.

- replace by simple quotes in mass balance output strings
Fixed mass balance for linear reactions and decays.
Merge remote-tracking branch 'origin/DF_balance_output' into JS_mass_balance
Correction to balance of linear reactions.
- sources multiplied by cross section
- coefficients precomputed only when data change
Fixed mass balance for dual porosity.
Fixed mass balance for sorptions.