Setup of code coverage measurement

[mcavigelli]

As software developers we want to see how good our code is covered by automated tests. That's why we measure code coverage.

Currently our appveyor build does not measure it. It was enabled, but slowed down the build by factors (also seen on my local machine).

Support was removed in the following commits:

1. 89aba1b Removal of opencover and upload to coveralls
2. bb2b00a Updated info in Readme.md

Tasks to be done

• [ ] Measurement (opencover or similar)
• [ ] Visualization of result (coveralls, other report, or similar)