OBStools: Software for processing broadband ocean-bottom seismic data

This release fixes a number of issues with the spectral calculations, plotting functions, channel descriptions and data handling. These changes appear mostly in the codebase, the scripts being largely un-touched. Changes include:

• Windowed Fourier transform is now calculated with scipy.signal.stft, for the QC steps and other spectral calculations. This ensures all windows are the same and avoids loading the scipy.signal.spectrogram and renders the utils.sliding_windows function obsolete.
• The full spectra are now kept in memory, as opposed to truncated spectra for the positive frequencies. This avoids potential bugs but increases the size of objects saved to disk.
• All example data are now provided in SAC format and no longer in .pkl files, which avoids pickle version conflicts.
• All scripts and functions load seismic data in SAC data format and no longer save the EventStream objects as .pkl files.
• All functions are free of StDb arguments, improving flexibility in the API
• API docstring and documentation have been updated