BeforeTestRun resp. AfterTestRun added

[ThiAmm]

Methods annotated with BeforeTestRun resp. AfterTestRun will be executed before resp. after the execution of a Examplegraph.

[akuhn]

Looks like this file is missing .java extension.

[akuhn]

Hooray for contributing! 🎀

As mentioned in the issue this implementation might not be safe if a text class has test functions that depend on the return value from another test classes. But otherwise this looks good.

More see inline comments.

[ThiAmm]

Thanks for your answer.

I currently use methods annotated with "@BeforeClass" to create a directory and put some files in this directoy which will be needed for the the test. Clearly, i do want to delete the directory after running my tests.
So, after running the tests implemented with JExample, i recognized that my test directory still exists although i wrote a method annotated with "@afterclass" where i delete the directory.
After debugging i recognized another issue for me: Assume i haven written two classes A and B in which several tests are declared and a method annotated with "@BeforeClass". Furthermore assume tests in class B depend on tests in class A. When i run class B, the method annotated with "@BeforeClass" in class A might be called instead of the method annotated with "@BeforeClass" in class B. Therefore i created two new annotations "@BeforeTestRun" and "@AfterTestRun" which seem to have the behaviour i am looking for (instead of changing the behaviour of existing annotations).