- Roundtrip referenced XML nodes before c14n to detach them from pare…

…nt document when verifying (#225)

- Add type attribute to XAdES signed properties reference (#224)

- Use distinct default for payload c14n. Fixes #217

- Deprecate SHA1

- Test and documentation improvements

- Remove incorrect deprecation of xml-c14n11 URI

- Mark SHA1 as deprecated

- Aggregate verification settings in SignatureConfiguration dataclass

- Mark all dataclasses in API as frozen

- Add ability to assert expected signature location

- Add ability to assert expected signature algorithms

- Add ability to assert expected digest algorithms

- Add MGF1 ("RSASSA-PSS without parameters") algorithm identifiers

- Remove PSS ("RSASSA-PSS with parameters") and EdDSA algorithm
  identifiers (given low usage and no interop examples, we will not be
  implementing PSS parameters for now; EdDSA key info additionally has
  no standardized way to serialize it)

- Add debug logging of canonicalization outputs

- Documentation and formatting improvements

- Add XAdES support

- Migrate all configuration inputs to enums (string identifiers are still supported, but will be deprecated in a future version)

- Migrate structured data inputs to dataclasses

- Deprecate excise_empty_xmlns_declarations

- Documentation and test infrastructure improvements

- Clean up top level signxml and signxml.xades namespaces

- Stop using default_backend for cryptography, it is no longer required

- Drop Python 3.6 support (#200)

- Do not excise any empty `xmlns=""` declarations by default. This be…

…havior is now configurable as follows

  ```
  signer = XMLSigner()
  signer.excise_empty_xmlns_declarations = True
  signer.sign(...)
  ```
  ```
  verifier = XMLVerifier()
  verifier.excise_empty_xmlns_declarations = True
  verifier.verify(...)
  ```

- Documentation and autoformatting improvements

- Excise empty xmlns declarations only in signature, not in payload

- Add pyinstaller support to signxml (#188)

- Documentation, test infrastructure, and code organization improvements

- Unlimit cryptography version constraint. Fixes #177

- Bump pyOpenSSL compat range; add dep version strategy note

- Allow the combination of X509Data and KeyValue when they represent …

…the same public key (#169)

- Use self.namespaces signature properties "Object" element (#167)