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