Small improvements....

- Well, this isn't an improvement. I thought analyzer was detecting
something wrong but I wasn't right: it does as expected.

- Added a test file with 3 classes. They're correctly detected.

- Added a "C" class in a test "ns3" namespace. Its hierarchy is
correctly detected too!!

- Small fix: when more than a class was declared in the same file, while
they were correctly detected, they weren't present in the final result.