Loren-frank-data-processing

+ Minor fix to exclude multiunit spike times greater than the given epoch time

+ Some quick hot fixes to the functions for retrieving multiunit data

+ Made `get_all_spike_indicators` accessible from the top level of the package
+ Added new function for retrieving multiunit files that are formatted the same way as the spikes (i.e. Demetris's new format).

+ Quick fix so that `turn` and `linear_position` are interpolated in `get_interpolated_position_dataframe`

+ Add `turn` to the segments dataframe to capture whether the animal is turning right or left (0b0382a)
+ Change NaN for is_correct to False so that indexing with this field is easier (54ae16f)
+ Don't backfill interpolated position because now time is evenly spaced (75824f5)
+ Change failure to load file from error to warning in logger (89e0531)
+ Add linear position as a field in position_info (d571a65)

+ Use DIOs to segment trials and determine whether trials are rewarded (81f06626808a27e49cfc6182474fb91380460737)

+ Fix so that returns to the center well on an outbound trial are scored as incorrect (a3b541ee60ee0911b4b7b4e70ed4b0ea55db6ca4)

+ Require networkx >= 2.0 (6dc450e34a50994ff90e4d02c0b0790b81267e16)

+ Warn if file fails to load (7326c56a45a779833353bcb61f60ca4838616011)