add !pm stripify option

vendor/github.com/kvannotten/mailstrip/README.md

@@ -0,0 +1,35 @@
+# mailstrip
+
+mailstrip is a [Go][2] library that parses email text and strips it of
+signatures and reply quotes. It is a port of [email\_reply\_parser][1], GitHub's
+library for parsing email replies.
+
+## Differences to email_reply_parser
+
+Most of mailstrip is a line-by-line port of email\_reply\_parser and it passes
+all tests from the email\_reply\_parser test suite. However, it also implements
+a few improvements that are not part of email\_reply\_parser:
+
+* Forwarded fragments are detected and considered to be visible text, see
+  [d321c1][3].
+* Replies from Yahoo! which lack ">" quote indicators are handled correctly,
+  see [e844d][4].
+* Alternative quote headers used by gmail are handled correctly, see
+  [7ecb6][5]
+* Replies from Google inbox / gmail that has a quoute header in swedish(and possibly other languages) are handled. See [4128d][6].
+
+## Documentation
+
+The API documentation can be found here:
+http://godoc.org/github.com/kvannotten/mailstrip
+
+## License
+
+MIT License. See LICENSE file.
+
+[1]: https://github.com/github/email_reply_parser
+[2]: http://golang.org/
+[3]: https://github.com/kvannotten/mailstrip/commit/d321c10543f77c0beaacb40b04511e619f0652c6
+[4]: https://github.com/kvannotten/mailstrip/commit/e844df52342787c3cf2e0ebb8850b16e35f7f437
+[5]: https://github.com/kvannotten/mailstrip/commit/7ecb608981016c5633575cb93abb00e4c7370bcf
+[6]: https://github.com/kvannotten/mailstrip/commit/4128d1860b0b9477145ac4b4bbf14d1f072f7a4c