Updated test for generators to check that distance map is not recomputed when loaded correctly

Additional package msgpack-numpy needed for ndarray.
This saves tons of time when loading precomputed files.
Updated test to test loading and saving with and without distance maps

It now sets all the info from pickle file before running all the prediction and observations.
Also added a test for file load
UPDATE: Edited the test

It now sets all the info from pickle file before running all the prediction and observations.
Also added a test for file load