Use the certificate store to look up certificates

• sq inspect - inspect the specified certificate(s)
• sq key generate - optionally import the public key into the certificate store
• sq key userid add - optionally import the public key into the certificate store
• sq revoke - optionally import the public key into the certificate store
• sq key userid strip - use the specified certificate(s)
• sq key adopt - optionally import into the certificate store
• sq autocrypt import - new subcommand, or extend sq import to handle autocrypt encoded data
• sq keyserver get - by default save in the cerstore, export if --export is provided
• sq keyserver update - update some or all certificates
• sq wkd update - update some or all certificates via WKD
• sq dane - update some or all certificates via dane