cleaned up documentation

doc/doxygen/Doxylocal

dumux/decoupled/1p/diffusion/diffusionproblem1p.hh

dumux/decoupled/2p/diffusion/diffusionproblem2p.hh

dumux/decoupled/2p/transport/transportproblem2p.hh

test/boxmodels/1p/1ptestproblem.hh

test/boxmodels/1p2c/tissue_tumor_spatialparameters.hh

test/boxmodels/2p/lensproblem.hh

test/boxmodels/2p2c/injectionproblem.hh

test/boxmodels/2p2c/injectionspatialparameters.hh

test/boxmodels/2p2cni/waterairproblem.hh

test/boxmodels/2p2cni/waterairspatialparameters.hh

test/boxmodels/2pni/injectionproblem2pni.hh

test/boxmodels/richards/richardslensproblem.hh

test/boxmodels/richards/richardslensspatialparameters.hh