[implicit grid adapt] Generalize Initationalizationindicator to
arbitrary dimensions, element geometry types, and discretization scheme

The initilization indictor is simplified by only checking the midpoint
and the corner points of every element for a matching source or
boundary condition. This works for BOX and CCFV schemes. For the 2p
test the new indicator yields the identical result.

Reviewed by martins



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/branches/gridadapt@14588 2fb0f335-1f38-0410-981e-8018bf24f1b0