Test output files are written to ${CMAKE_BUILD_DIR}/Tests/Data.

As a WIP data files have to be in ${CMAKE_SOURCE_DIR}../data

This should also fix local VTK build with OGS_USE_PETSC.

Boost, VTK, Eigen
Closes #892.

This is the used by ExternalProjectVTK / -Catalyst.cmake

This will be used instead of the custom catalyst vtk editions making
it much more easier to add new vtk libraries to the automatic build,
see #869.

Catalyst will be used in the future but just for in-situ vis configs.

The marked variables will not show up by default in ccmake or cmake-gui
Enable them by pressing t or the advanced checkbox.

See
http://docs.opengeosys.org/docs/devguide/advanced/configuration-options

Was because of an outdated FindGit-module in ThirdParty/cmake-modules.

- Raised minimum CMake to 3.1 because of better crosscompiling support
  and imported target feature
- When Eigen is not found it gets downloaded before BaseLib is build
- Silenced OpenMP CMake output

Executables can be run with Wine.

Successfully runs both with and without gui.