Include new features, add links to models and test problems

*Fix errors
*Add .bib entry for citation

Handbook:
- don't use deprecated Latex commands \it and \bf
- use the \Cplusplus macro consistently

Doxygen:
- put FluidStates group to the right hierarchy level
- improve wording

*Use headlines to separate the individual sub-models
*Remove \copydetails Dumux::TwoPTwoCNIModel as this no longer
 exists

Modified formatting of descriptive text.

improve documentation for 2pnc and 2pncmin model and add description for classes
rename modules (sequential) and reorder according to new structure (porousmediumflow...)

All relevant description were taken from the Handbook and added to/merged with
existing doxygen descriptions

- Moved all general descriptions to doxygen.
- General descriptions were included in modules.txt
- New groups had to be added in modules.txt:
	-ConstraintSolver
	-EOS
	-ParameterCache

only the ni-base-model will be listed in the module list
ni-test-problems include docu from non-ni-base problem

- added FluidState group, which appears now on the module page
- fixed ingroups


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15432 2fb0f335-1f38-0410-981e-8018bf24f1b0

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15066 2fb0f335-1f38-0410-981e-8018bf24f1b0

doxygen
- added zeroeq and multidomain models
- add model and problem descriptions

handbook
- changes in the model description of models which do not use a free
  flow are just related to changes in doxygen
- added equation subsections for multidomain and zeroeq models

naming
- applied naming convention to stokes, zeroeq, and multidomain
  models/problems

reviewed by fetzer



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15023 2fb0f335-1f38-0410-981e-8018bf24f1b0

- Rename mainpage, modules and parameterlist to *.txt
  to work around new behavior in Doxygen 1.8.8 or newer.
- Fix missing closing brackets in brine_co2.hh.
- Add missing ! in plotoverline (by fetzer)
(reviewed by fetzer)


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@14763 2fb0f335-1f38-0410-981e-8018bf24f1b0

updated doxygen docu, there are still 7 warnings are produced


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@13381 2fb0f335-1f38-0410-981e-8018bf24f1b0