Code simplification and optimizations

[sorc1]

I'm using C part of py-radix in my projects. So, I need all the algorithm to be in a separate library. For now, some useful functions (Radix_search_covered(), for example) are not parts of a radix library but are parts of C-Python glue. Some are just private (static) functions.

So, the main target was to extend C radix library with new functionality. Other things done:

• Removed code duplication in many cases (introduced some useful macroses)
• Added prefix_pton_ex() & prefix_from_blob_ex() to allow to not allocate heap memory for prefix to use search functions
• Reimplemented radix_search_covered() with improved algorithm

[mjschultz]

Sorry about the delay, I've pushed your changes to PyPI so you can now do pip install py-radix==0.9.1

[mjschultz]

Thanks!

[sorc1]

Thank you!