In particular remove non-recommended installation command that also
contained an outdated --use-cmake option which doesn't exist anymore.

debug.opts and optim.opts do not exist anymore. This commit adapts the
respective section in the handbook.

Johannes Hommel authored Nov 28, 2018 and Martin Schneider committed Dec 18, 2018

[handbook] updated 'getting started' chapter, split in 'quick start' and 'detailed installation, documentation and externals'

Handbook/improvements for release

See merge request !411

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

changed the dune version to the most recent (2.4.1) in the detailed installation section.

Updated the folder structure description and the installation instruction in the handbook.

added the new minimum compiler and cmake requirements