add scripts to estimate audio segmenting parameters for canaries, fix #142

[NickleDave]

• add src/scripts/Canaries/generate_segment_feature_vals_csvs.py that creates csv files from pandas DataFrames containing values of segment features in the ground truth manually-annotated data: the amplitude at onset + offset, segment durations, and silent gap durations
• add src/scripts/Canaries/estimate_seg_params.py that uses the csv files saved by generate_segment_feature_vals_csvs.py to come up with a "least-bad" estimate of parameters for segmenting audio. Uses 10th quantile for minimum segment duration / silent interval as suggested by @yardencsGitHub