• Add missing xenc:EncryptionProperty and xenc:EncryptionProperties elements (#47)
• Stop formatting signed elements (#52)
• Prefix filenames with file:// if necessary, or openssl will fail (#54)
• Add element registry (#55)
• Properly validate nested signatures (#51)

Many, many changes under the hood.
Sorry, changelog will be started from this point on!

Most significant change:
#44