GC-88: General Discrete Distribution estimation function couldn't handle observations with negative values.
Adding new imaging filters contributed by frameworks users: Difference of Gaussians, HighBoost, Niblack Threshold and Sauvola Threshold.
Adding support for directly processing matrices in the Normalization filter.
Adding a 2D Kalman filter implementation contributed by frameworks users.
Correcting kernel distance computations and adding support for explicit feature space transformation in some kernels.
Working on documentation.