This regression seems more severe than the bug the commit was
attempting to fix (incorrect parsing of nested wikilinks in normal
links), so that bug is reintroduced until localization-aware parsing
that allows us to detect file links is added.

This commit partially reverts fac60dee48.

Signed-off-by: odidev <odidev@puresoftware.com>

* Proposed fix for https://github.com/earwig/mwparserfromhell/issues/197

* Port the fix for #197 to the C tokenizer

* Fix parsing of external links where the URL is terminated by some special character

- One existing test case has been found wrong -- current MediaWiki
  version always terminates the URL when an opening bracket is
  encountered.
- Other test cases added: double quote, two single quotes and angles
  always terminate the URL (regardless if it is a free link or external
  link inside brackets). One single quote does not terminate the URL.

* Fix case-insensitive parsing of URI schemes

It's EOL and AppVeyor builds are broken under it if we want to support Python 3.9.

Not fully deprecating 3.5 for now because it's still used on Toolforge.

Fixes #198

Co-authored-by: Ben Kurtovic <ben.kurtovic@gmail.com>

* nodes: add a `default` param to Template.get

Similar to dict.get, Template.get with a default param supplied will
return that value instead of raising an exception. If default is unset,
Template.get will keep its previous behavior and raise an exception.

* nodes: Add __getitem__, __setitem__, and __delitem__ to Template

These are just aliases for existing methods, without the ability to
specifiy additional parameters. However, including them makes Template
more dict-like, so it's a good idea to have them.

* nodes: Use def instead of assignment of a lambda in Template

Per PEP8, there is no benefit to using a lambda here, and some
downsides. It's the same number of SLOC either way, so might as well
change it.

Use Github Actions to build macOS wheels too

For 3.5+ on the latest macOS version.