GitLab

* Add new deploy job creating an environment for every release branch,
  merge request, and the master branch.
* Add environment stop job removing the environment after it has been
  stopped (happens automatically if branch is deleted).

Run ODE tests now with upwinding options of FV and DG solver
where a change of the residual tolerance limit was not necessary.

Several adjustments were made to make applying local operator options
easier:
* Remove 'EXPERIMENTAL_DG_FEATURES' option. Settings in config file
  now apply by default.
* Move previously experimental options to 'richards.numerics' section.
* Rename settings 'method' to 'DGMethod' and 'weights' to 'DGWeights'.
* Fix typo: Rename OOB to OBB scheme (Oden, Babuska, Baumann).

ModelFactory currently compiles separately, i.e., without linkage to
the 'impl' library. This vastly reduces the amount of code in the main
function.

* Include latest version of Google Test as Git Submodule.
* Link Google Test to all DORiE unit tests. This has no effect if its
  header file is not included.
* Enable testing in DORiE if dune-testtools is found.
* Update SimulationBase unit test to work with Google Test.
* Add Doxygen docs on unit testing.
* Update README.md.

Fetch the enclosing multi indices with the coordinates in mesh units,
not physical units. Improve the unit test to cover more complicated
cases, thus ensuring that the interpolator works as intended.

* Update Dockerfile for base image
* Bump Docker base image to v1.2
* Update version info in README.md
* Update CHANGELOG.md

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Generalization of initial condition specs leads to a change in the API,
but it is no new addition to the program.

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Signed-off-by: Santiago Ospina <santiago.ospina@iup.uni-heidelberg.de>

Signed-off-by: Santiago Ospina <santiago.ospina@iup.uni-heidelberg.de>

Signed-off-by: Santiago Ospina <santiago.ospina@iup.uni-heidelberg.de>

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