GBNN-matlab v2.0: pull from experimental branch

Lots of changes, the framework is more stable, has more parameters and functionalities and better plots. Here is a non-exhaustive changelog:

- tagged networks, with theoretical error rate. Also works for concurrent cliques problem.
- disequilibrium trick for concurrent cliques problem.
- dropconnect.
- subsampling.
- database search (to find the most similar learned message compared to the decoded message).
- lots of new measures like matching or similarity scores.
- beautiful plots, relative to density instead of messages, with parameters to tweak them.
- MOAR comments.
- unit-testing to check that everything is alright (error rates are OK, compatibility with MatLab, no regression in functionalities when adding new ones, etc.).
- possibility to specify density of the network to learn, instead of having to specify an exact number of messages (great to test error rate depending on density).
- lots of theoretical metrics computed automatically via gbnn_theoretical_stats.m
- lots of tweaking, bug fixing, etc.

Enjoy!