Add CB

Add/update/improve CB (continuous benchmarking). For this, the CI is extended to run checks and performance runs on JUSUF, then evaluate the results and produce static HTML pages via mkdocs. A first, not too serious badge is also generated that has a score from the benchmarks. The score is based on random run of the master branch. This could be based on a benchmark run of a released version. Other branched will be compared against the master branch.

The results are (currently?) stored in a branch (continuous_benchmarking) within the repository, branch by branch. This may be too error prone in the long run, will see how it develops. This branch also holds/generates a container image with the required tools.