Typo.
Add an option to specify a default language for code.

Fixes https://github.com/pw374/omd/issues/48
Allow spaces after the language name in code blocks.

Example:
```lang
code
```

This is compatible with the way pandoc and Github deal with such
spaces.
Make code_stylist a function instead of an object.

Fixes https://github.com/pw374/omd/issues/53
Add a function to set the code language when unspecified.
Merge pull request #54 from Chris00/master

Default language for code & code stylist