* Made multitron accept array of integers instead of list
* Refactoring/cythonising multitron. Slightly broken, -0.2 accuracy. Investigating.
* Substantial bug fix: ignore 0-value features, as they're code for omitted
* Small efficiency tweaks
* Setting aside pruning feature index for basic one for online learning, as pruning doesnt make sense for dynamic training
* Refreshed add_amb_instance. Added parameter for number of features
* Made labels and label_to_i arrays.Added comment
* Begining online learning experiments