Trampoline Overridden Method duplication prevention

Previously, a method that was a candidate for trampolining, but had a string representation created by pygccxml different from it's parent class' method (different argument names, typedef'd args, etc) would be duplicated in the trampoline, resulting in compiler failures.

This MR prevents that from occurring by using pygccxml's function traits module for direct comparison to determine if the base and derived class methods are true overrides.

Current solution is a little naive, would like to optimize, but that can be left to a later date if we feel merging this in is more important.