updated / corrected / introduced doxygen documentation

mpncmodelkinetic: 
- ask volVars instead of fluidState for temperature (sPhase is not stored in fluidState)
- add output to checkplausibility

mpnclocalresidualenergy:
removed unused functions 

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@11468 2fb0f335-1f38-0410-981e-8018bf24f1b0