* Disable Linkchecker Test.
* Switch to unittest.mock in standard lib.
* Apply `pyupgrade --py3-plus`.
* Note: Using `builtins.open` mocks all calls to `open`, including test setup
(such as in `load_config`). Whereas, `path.to.namespace.open` only mocks
`open` in that namepsace. This all worked differently when we used `io.open`
as that wasn't a builtin to begin with.
* Add a helpful error msg for PY2 users who use non-standard install methods.
Closes#1926.
Fixes#782. Note that we mock Markdown in the tests to ensure those
tests are not using Markdown to validate the extension names. We don't
mock Markdown in the tests which we do want Markdown to validate the
extension names.
Also ensure project-min has all relevant extensions.
This change removes the dependency on mkdocs-bootstrap and mkdocs-bootswatch.
It also updates all references in the code. The only remaining connection is
when a user specifies one of these themes but they are not installed they get
slightly helpful error.
This reimplements the CLI interface to use Click, which in turn gives us
a much easier to use interface as it provides help messages for all the
commands and individual commands.
Fixes#259
