Import yaml-cpp-0.5.1 as wip/yaml-cpp.

yaml-cpp is a YAML parser and emitter in C++ matching the YAML 1.2 spec.
Add yaml-cpp to Makefile
Import py27-cxnet-0.3 as wip/py-cxnet.

The cxnet extends IGraph module with some functionality
I am using in higher education.
Some functionality is available with NetworkX module as well.
Function plotting needs matplotlib (pylab).

Functionalities:
- Creating networks with multifractal network generator.
- Creating network from the deb package hierarchy.
- Investigating and plotting degree distribution.
- Graph methods:

 * to list the vertices with most degrees,
 * to plot the neighbours of a vertex.

- A tool to create network evolution models