Have run() return a struct

@Joseph has added a struct to machinelearning.h which could hold many types of possible algorithm outputs. How far to integrate this into the whole API?

/** @brief A generic ouptut struct to fit all kinds of models */
    typedef struct runResults_t {
        std::vector<double> likelihoods;
        std::vector<double> regression;
        std::vector<double> progressions;
        std::string likeliest;
    } runResults;