schemes. 

Added files for adaptation in subfolder implicit/adaptive. The implicit
properties inherits from GridAdapt properties. Basic functions are
included in the implictproblem. The beginUpdate() function is modified
such that the JacobianMatrix is updated after each grid adaptation. The
grid adapt is done in the preTimeStep() method, make sure to call the
parent function when overwriting this method. 

TO make a testproblem adaptive, just set the property AdaptiveGrid to
true and choose corresponding indicators via
AdaptationInitializationIndicator, AdaptationIndicator (see
TwoPTestProblem). 

Restrictions: no parallel solving yet and problems with solvers using
gridView informations.

Reviewed and discussed with Timo  


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@14619 2fb0f335-1f38-0410-981e-8018bf24f1b0