Mkdocs-macros-plugin

* Fixed: (118) `{{ git.date }}` is now committer date (no longer author date).
* Added: new git info elements (author email, committer, committer email);
documentation was updated
* Added: by default, unknown variables in a markdown page (`{{ foo }}`)
are no longer replaced by blanks but displayed as is (DebugUndefined) (117);
for better compatibility with other plugins or error detection
* Added: `on_undefined` parameter in plugin definition to alter behavior
with unknown jinja2 variables: 'keep' (default), 'silent', 'strict', 'lax';
documentation was updated

* Fixed: Broken build of 0.6.2

* Added: `env.markdown` is now modifiable, for use in `on_post_page_macros()`

* Added: auto-install of pluglets (in `module` parameter in config file)

* Fixed: documentation (for readthedocs) now contains proper
link to edit uri on github
* Fixed: broken link in webdoc/docs/pages.md
* Bump version to 0.6.0, to acknowledge the breaking change in 0.5.10

* Fixed: Incompatibility with mkdocs 1.2
(`on_serve()` event, call to `server.watch()`)