Upgrade the encryption algorithm on another thing. This uses the same PBES2 parameters as the previous one.

If someone has a choice for a 2nd algorithm, I'm happy to do that. See previous PR for ideas about how to review
Update docs
Merge pull request #1484 from alex/re-encode-thing

Upgrade the encryption algorithm on another thing. This uses the same PBES2 parameters as the previous one.
fixed a syntax error in the docs
Merge pull request #1485 from alex/docs-syntax

fixed a syntax error in the docs
A handful of different fixes for the interface docs
Merge pull request #1486 from alex/docs-fixes

A handful of different fixes for the interface docs
A few more docs fixes
Merge pull request #1487 from alex/more-docs-fixes

A few more docs fixes
Initial minimal X509Certificate interfaces

This will be expanded in the future to include algorithm identifier,
subject, issuer, extensions, etc
add backend interface for loading x509 certificates