Enable running tests in parallel

[Chemaclass]

Investigate how could we enable running tests in parallel.

Tech hint

Multithreading is not possible in bash, but...

You can run a process in the background with & and then make the main process wait for all its children with wait.

Consider storing each test result in a temp-file (within a temp-folder for each test script), and then at the end read the result of each test to know the totals of the test execution.