Use PyPI token

this is 0.7.1

Updates for a 0.6b1 release

Resolves #5
Resolves #22
Resolves #27

click<8

Note changes

Last readme updates.

Add a change log, increment version, and note proper license.

The text in our LICENSE file was BSD, but the setup metadata said
MIT. It now says BSD.

More explanation of sequences and RS.