Mkdocs-redirects

* Fix deprecation warning about `warning_filter`

* For better interoperability with plugins, the redirect target paths are picked up from the corresponding MkDocs `File` and not re-computed by simple substitution. (45)

* Drop Python 2.7 support

* Bump minimal MkDocs version to 1.1.1

* Remove warning about old `redirects` config

* Redirect destination paths can now contain fragments (42)

Example config:

yaml
plugins:
- redirects:
redirect_maps:
some/path/examples.md: foo/index.mdexamples


-- this will now correctly redirect to `foo/examples` without messing up the path

Note that this applies only to the *destination* paths, there's still no handling for fragments in *source* paths (those specified as map keys).

* Correctly use UTF-8 file encoding even on Windows (41)

* Normalize only capitalized `README.md` files to `index` (37)

- Transferred ownership of the package to mkdocs organization.
- Fix regression from 1.0.2 when handling index pages with `use_directory_urls: false` (25)
- Fix the content of produced redirect pages on Windows (34)