Checkdmarc

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- Replace publicsuffix2 with publicsuffixlist (PR 92)

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- Maintain the original character case of the DMARC record
- Always treat tag names as lowercase
- Always treat the DMARC `v` tag value as if it was uppercase
- Always treat the DMARC `p`, and `fo` tag values as if they were lowercase
- Always treat URI schemes as lowercase, but maintain the case of the address
- Remove inaccurate `testInvalidDMARCfo` test

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- Ignore case and whitespace when parsing DMARC and BIMI key=value pairs (Closes [75](https://github.com/domainaware/checkdmarc/issues/75))
- Handle missing `PTR` records more gracefully (Closes [64](https://github.com/domainaware/checkdmarc/issues/64))
- Redundant DMARC `fo` tag values now result in a warning instead of a syntax error (Closes [71](https://github.com/domainaware/checkdmarc/issues/71))

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- Detect non-trivial loops (PR [88](https://github.com/domainaware/checkdmarc/pull/88))
- Raise a `SPFSyntaxError` exception when an IP address and IP version do not match (PR [87](https://github.com/domainaware/checkdmarc/pull/87))
- Fix raising the `DMARCRecordNotFound` exception when a DMARC record does not exist (PR [86](https://github.com/domainaware/checkdmarc/pull/86) closes issue [#72](https://github.com/domainaware/checkdmarc/issues/72))
- Add void lookup limit (PR [85](https://github.com/domainaware/checkdmarc/pull/85))
- Add Support for User Defined DNS Resolver Object (PR [83](https://github.com/domainaware/checkdmarc/pull/83))

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- Fix DNS caching (issue [79](https://github.com/domainaware/checkdmarc/issues/79) PR [#80](https://github.com/domainaware/checkdmarc/pull/80))

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- Fix tarball build (78)