[docker] add Dockerfile

See merge request tools/frackit!182

This ensures that not all artifacts are downloaded

We allow for passing the number of entities to be created via the
command line, such that this can be used in the test suite to speedup
computations.

This turns examples into "tests". We actually want to have them tested
in the ci as well. Moreover, the add_application macro was basically the
same as add_test, just not adding an actual test.

Feature/docu improve installation notes

See merge request tools/frackit!180

[ci] use default image and specify only mrs for all jobs

See merge request tools/frackit!181

[CMakeLists] improve OCC lib search

See merge request tools/frackit!179

Feature/support occ 7.5

See merge request tools/frackit!178

This enables the user to set a search path for OCC in case of custom
installation folders. Moreover, one has the possibility to link other
OCC libraries in case they are needed for an application.

According to the OCC docu, generated shapes are only those that do not
have the same dimension as the shapes participating in a boolean
operation. Thus, inserting them as fragments here leads to errors in the brep
writer and is not what we want. In OCC7.5 this fails while OCC7.3 did
not have issues with this for some reason.

[ci] test python bindings too

See merge request tools/frackit!177

[ci] run tests in parallel

See merge request tools/frackit!176

Feature/improve ci

See merge request tools/frackit!175

[doxygen] exclude python-bindings from docu

See merge request tools/frackit!174

Feature/gitlab ci

See merge request tools/frackit!173

[paper] add more references and edit quad sampler section

See merge request tools/frackit!171