Pyndl: Naive discriminative learning in python

• adds Widrow-Hof learning on Linux (real_to_real, real_to_binary, binary_to_real)
• adds fast correlation code
• drop python 3.6 support and add python 3.9 support
• changes API from number_of_threads / number_of_processes to n_jobs
• exposes make_data_array as ndl.data_array(...) and adds tests
• adds learning events from generators in ndl.ndl
• changes tuples into namedtuples for return values
• adds sanity check for too many cues or outcomes
• checks if outcomes_vectors, cue_vectors and weights are c_contiguous before passing it to cython functions
• adds scipy, packaging as dependencies

Co-authored-by: Elnaz Shafaei elnaz.shafaei@gmail.com and Marc Weitz marc.weitz@onlinehome.de