Improve Spliceout

[iver56]

Here are some ideas for Spliceout improvements:

• [ ] Add a param for crossfade window size? 10 ms may actually be a bit on the large side for a default
• [ ] Maybe try sqrt for crossfades instead of hann to avoid the perceived dip in energy in the crossfades
• [ ] Improve the docstring (ELI5)
• [ ] Rename max_width? And specify it in seconds instead of milliseconds.
• [ ] Run black on the code
• [ ] Mention it in README
• [ ] Update changelog