JS mass balance  - second 

Yet need to deal with changes in deleted files:
linear_reaction.cc
linear_reaction_base.cc
These methods are quite similar to what I have suggested earlier - see the top of sorption.h. The isotherm_reinit methods only differ in computation of scale_aqua and scale_sorbed in terms which are exactly computed by these methods. The reason why we left it this way was, that Honza did not want to bring inside compute_reaction another virtual calling, although the interpolation table might be used most of the time (when rock density and porosity is constant). At least, we could read the values from fields and compute these terms only once.