remove unused private typedefs from dumux/geomechanics and test/geomechanics

dumux/geomechanics/el1p2c/el1p2celementvolumevariables.hh

dumux/geomechanics/el1p2c/el1p2cfluxvariables.hh

dumux/geomechanics/el1p2c/el1p2cmodel.hh

dumux/geomechanics/el2p/el2passembler.hh

dumux/geomechanics/el2p/el2pelementvolumevariables.hh

dumux/geomechanics/el2p/el2pfluxvariables.hh

dumux/geomechanics/el2p/el2plocaljacobian.hh

dumux/geomechanics/el2p/el2plocaloperator.hh

dumux/geomechanics/el2p/el2pmodel.hh

dumux/geomechanics/el2p/el2pnewtoncontroller.hh

dumux/geomechanics/el2p/el2pvolumevariables.hh

dumux/geomechanics/elastic/elasticfluxvariables.hh

dumux/geomechanics/elastic/elasticlocalresidual.hh

dumux/geomechanics/elastic/elasticmodel.hh

test/geomechanics/el1p2c/el1p2cproblem.hh

test/geomechanics/el1p2c/el1p2cspatialparams.hh

test/geomechanics/el2p/el2pproblem.hh

test/geomechanics/el2p/el2pspatialparams.hh

test/geomechanics/elastic/elasticmatrixproblem.hh