OpenGeoSys 6.1.0

The following notable changes and new features were implemented between OpenGeoSys 6.0.8 and 6.1.0:

New equation assembly approach for the staggered scheme. With that, the coupling assembly computations are changed from performing assembly across the different Process classes for a coupling to a single Process class for coupled processes, which was assumed only for the monolithic before. With the changes, the original Process class that for monolithic scheme originally can now handle both of the monolithic and staggered schemes. So far, HT classes get the staggered scheme based on this new framework of assembly. https://github.com/ufz/ogs/pull/1970
Heterogeneous liquid flow properties #1979, #2017
New boundary conditions added: Nonuniform Dirichlet (https://github.com/ufz/ogs/pull/1952) and Neumann (https://github.com/ufz/ogs/pull/1891), and normal traction (https://github.com/ufz/ogs/pull/1896)
Framework for time stepping and a first application of adaptive time stepping, EvolutionaryPIDcontroller, and automatic time step control (https://github.com/ufz/ogs/pull/1803).
Nodal source terms (https://github.com/ufz/ogs/pull/1977)
Fix deformation processes to work correctly with PETSc parallelization (https://github.com/ufz/ogs/pull/1838).
Fix the access to local data of PETScVector (https://github.com/ufz/ogs/pull/1797).
Add damping factor to global Newton. https://github.com/ufz/ogs/pull/2004
Extend extrapolator to vectorial quantities and replace the component-wise output of Darcy velocity and the stress/strain in mechanical processes with single vectorial output.

Insitu visualization with ParaView Catalyst. #1744, #1732. As a consequence VTK 7.1 is now required.
Benchmark docs are now part of the code (in web/content) and can contain interactive 3D visualizations via vtk.js. #1706, #1714, #1723, #1729.
Migrated handling of test data files from git-submodule to git-lfs, see docs. #1964, #1982, #1984, #2010, #2012. Now git-lfs is required. Check the installation instructions.

Fully moved to Conan for automatic third-party library handling. Can be enabled with OGS_USE_CONAN=ON, see docs. #1907
Conan version 1.0 is now required.
Dropped travis CI environment and added few new tests on Jenkins because of simpler maintenance.

OGS_EIGEN_DYNAMIC_SHAPE_MATRICES defaults to OFF on Release config, ON otherwise. Can be overridden by explicitly setting the option. #1673
New OGS_EIGEN_INITIALIZE_MATRICES_BY_NAN defaults to ON for easier spotting of non-initialized matrices. When OFF, the Eigen’s default initialization to 0 is skipped resulting in slightly faster execution. https://github.com/ufz/ogs/pull/1917
Set default Eigen’s cmake flag disabling vectorization since this lead to several problems in different environments. https://github.com/ufz/ogs/pull/1919 and the issue linked there https://github.com/ufz/ogs/issues/1881