Documentation reaction term introduction added.
Merge branch 'output_master' of https://github.com/flow123d/flow123d into PE-reactions-output
Record substances moved to SorptionBase (not needed in DualPorosity and chemistry).
Renaming fields in DualPorosity.
Renaming fields and others in Sorption.
Rename Reaction base class, introduce reaction_term.
Renaming por_m to porosity.
Mass balance temporary fix - works only without reaction term.
Fix ReactionTerm parallel outputs objects and inovate test03.

- fix setting initial condition in DualPorosity and Sorption
- fix parallel output objects in DualPorosity and Sorption
- test03 - replace old dualpor and sorption keys
Reference manual missing figures - forgot to add.
New reaction term introduced in all tests.
TOS - old reactions removed, old test(20,23) reference data removed.
Old fields and keys for dualpor and sorption in convection_transport removed.
Merge branch 'output_master' into PE-reactions-output