Add support for class/struct/union specific location

[Syllo]

Hey,

Nice project!

I encountered a wrong #include text while generating the documentation (the hyperref is good). Doxygen allows the user to specify a specific include path and your script did not extract the correct information from the xml. Fortunately this info is present inside the <includes> tag.

This is somewhat related to #137. Because the path in <location file="xx"/> is not stripped using the STRIP_FROM_INC_PATH option (otherwise we would have a problem referencing the files).

That is, there is still an issue for the path displayed in the text for functions, enums, typedefs, variables and defines which are not part of a class/struct or union. I believe that this was a custom addition of yours and Doxygen doesn't provide the tag for these unfortunately.

A fix to the latter would involve something as provided in #139, but where the paths in STRIP_FROM_INC_PATH are also stripped of STRIP_FROM_PATH beforehand to mimic Doxygen behavior (because the paths in <location file="xx"/> are already stripped of STRIP_FROM_PATH).

[Syllo]

I added the support for STRIP_FROM_INC_PATH in a second commit if you want that too.