DOM like API for Clang Python binding.

This library is not targeted to 100% correct C++ program parsing, simply it's too hard and not that useful for general use.

It's suitable for quick analysis of C++ files and as data source for auto-completion plugin for editors.

1. Set LD_LIBRARY_PATH to include libclang.so path. Usually you can get it by LD_LIBRARY_PATH=$(llvm-config --libdir)

2. Support libclang 3.6 for now. Will extend to 3.2 to 3.5.

WIP