[implicit] complete and test dim < dimWorld capability

All implicit porous-media models except 2pdfm are now able to run on
grids with dim < dimWorld. This still required some replacements of dim
by dimWorld, for example, in the velocity output of all models. In
implicit/1p, four new tests are added that run the 1p test problem on
1d-2d and 1d-3d Alberta grids with box and cell-centered, respectively.
Compilation has been tested also for all other models, but no runtime
testing has been performed.

This completes FS#183. Based upon preliminary work and a patch by
Natalie, thank you.

Reviewed by Natalie.


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@14110 2fb0f335-1f38-0410-981e-8018bf24f1b0