Move the longer ClangUtils functions to an own .cpp file
remove unnecessary else -> reduce intentation
Fix ClangUtils::getLeastQualifiedName

It should iterate over targetTypeQualifiers and not over
containingScopeQualifiers.

In the test case these were the same, however this is not necessarily
the case.
Add dedicated test for using directives
Print the number of of differences in tests
Initial support for handling using directives (#17)
Make sure that only using namespace directives before the call are used
update test case for #17 with more cases
Don't use llvm::Twine for appending itself, that crashes
Once a using namespace for the current namespace is found end the loop


Otherwise with 'using namespace NS::Nested;' it would create
&NS::Bar::signal instead of the correct &Bar::Signal;
Add more cases to test for #17
Also handle normal using directives: fixes #17

The only case that is not handled yet is using directives inside the
function that calls connect, however this is less common than global
using directives and is therefore created as a new low-priority issue