[license] add SPDX headers to Doxygen

[license] use CC-BY-4.0 for handbook documentation

[license] bulk license .md documentation with CC-BY-4.0

[license] use CC-BY-4.0 for example documentation

update of chapter 4+5
 - restructured and combined different sections
 - shortened text

done by gruenich and fetzer


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15168 2fb0f335-1f38-0410-981e-8018bf24f1b0

Restructured handbook and handbook files as we discussed
it in the handbook meeting. This change is hardly reviewable
so please compile and check whether you miss something in the
new version of the handbook or the structure appears weird.

The models have been removed, because they are just a copy from the
doxygen description and we decided to refer to the doxygen homepage
for a detailed description (which also upgrades doxygen).



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@15030 2fb0f335-1f38-0410-981e-8018bf24f1b0

updated handbook:
- added CMake instruction, removed autotools specific parts
- restructured Guidline, TipsNTricks and Detailed Intruction section
- colorful DuMuX code
- small updates in TipsNTricks



git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@14497 2fb0f335-1f38-0410-981e-8018bf24f1b0