[handbook] use new test folder structure

doc/handbook/2_quickinstall.tex

@@ -41,7 +41,7 @@ the results using ParaView. We recommend looking at a basic single phase groundw
 \begin{enumerate}
 \item Navigate to this test in the build directory using:
 \begin{lstlisting}[style=Bash]
-cd DUMUX/dumux/build-cmake/test/porousmediumflow/1p/implicit/isothermal
+cd DUMUX/dumux/build-cmake/test/porousmediumflow/1p/isothermal
 \end{lstlisting}
 \item Build the executable with the following command:
 \begin{lstlisting}[style=Bash]

doc/handbook/6_inputoutput.tex

@@ -17,7 +17,7 @@ complex DGF files, we recommend to write your own scripts, e.g, in \Cplusplus, M
 
 The DGF format can also be used to read in spatial parameters defined on the grid. These parameters can
 be defined on nodes as well as on the elements. An example for predefined parameters on a grid
-can be found in \texttt{dumux/test/porousmediumflow/co2/implicit/}.
+can be found in \texttt{dumux/test/porousmediumflow/co2/}.
 
 \subsubsection{Gmsh Mesh Format}
 Gmsh is an open-source flexible grid generator for unstructured finite-element meshes (\cite{GEUZAINE2009}, \url{http://geuz.org/gmsh/}).
@@ -36,7 +36,7 @@ Such grids consist of hexahedra, which are described by eight points on so-calle
 Furthermore, petrophysical properties can be defined (for each cell), by using eclipse-specific keywords, e.g. \texttt{PORO}, \texttt{PERMX}, \texttt{PERMY}.
 
 \Dumux supports the Eclipse Grid Format by using the \texttt{opm-grid} module (see (\url{https://opm-project.org}).
-An example can be found in \texttt{dumux/test\allowbreak/porousmediumflow/2p/implicit/cornerpoint}.
+An example can be found in \texttt{dumux/test\allowbreak/porousmediumflow/2p/cornerpoint}.
 
 \subsubsection{VTK File Format}
 VTK format uses ASCII or XML format. It is mostly used by \Dumux for output purposes and can be visualized by programs such as Paraview, ViIt or Tecplot. Using VTK files to input grid and parameter data is also possible.