Mistletoe

**Features**:

* shortened `mistletoe.markdown` keyword argument name (`renderer_cls` to `renderer`);
* removed List reference lookup;
* list items can contain paragraphs (CM5.2);
* shorthand syntax added for tables (26).

**Fixed**:

* ignored invisible characters at line end for `CodeFence` (24);
* fixed extra newlines for headings in JIRARenderer (25, thanks huettenhain!);

**Development**:

* moved documentation to `docs` directory;
* solved the biggest mystery in the codebase.

**Fixed**:

* `contrib/md2jira.py` was importing from the wrong directory (20, thanks to cctile);
* characters in LaTeX `lstlisting` environment should not be escaped (23, thanks to liuq).

**Features**:

* added JIRA Markdown support (thanks to cctile);
* `Strong` / `Emphasis` elements must open with non-whitespace characters;
* no more than 6 levels of `Heading`;

**Fixed**:

* `render_table` crashing when iterating token.children (12);
* `FootnoteLink` engulfing trailing spaces (14);
* `Paragraph.read` not stopping before CodeFence (15);

**Development**:

* added testing for CommonMark compliance;
* merged `plugins` directory into `contrib` (thanks to huettenhain);

Lastly, I miss cheeseburgers. 🍔

**Features**:

* `BlockToken` is a hell lot more flexible now;
* `add_token` accepts an additional position argument;
* Newlines are now preserved in `Paragraph` tokens.

**Fixed**:

* `ASTRenderer` fails to serialize `FootnoteAnchor`.

**Where I broke backwards compatibility**:

* `BlockToken` now has `start` and `read` methods, instead of `match` method. This allows for much more granular control of parsing when defining custom block-level tokens.
* `Heading` and `SetextHeading` are now different token classes, though their renderer functions are still the same.
* `CodeFence` and `BlockCode` are now different token classes, though their renderer functions are still the same.

**What has been in my life for the past few weeks**:

❄️

**Features**:

* added support for empty or self-closing HTMLSpan;
* added `--renderer` flag for command line usage;
* `token.children` now has idempotent behavior!

**Development**:

* refactored command line functionalities;
* testing and error handling.

Merry Christmas! 🎄

**Features**:

* removed argument `footnotes` from render functions;
* make custom tokens usable without invoking renderer as context manager (5).

**Development**:

* documentation updates and bug fixes (more to come!);
* refactoring and slight performance gains.

Now for a beer emoji: 🍺