Allow the testsuite-tags to be nested in the xunit-report.
Reasoning:
a) there are C++ frameworks which allow such structures (boost)
b) Junit-Reports can have nested testsuite tags too
solution for #218 / first version you can give a try
* all files without coverage report are set to 0 coverage
* use non comment lines of code for coverage calculation
* all lines of the files are marked red (also comments and preprocessor directives)
* source and header files included - with header files I'm not sure (but there could also be code inside)?