Blocks
------
Must be terminated by \n or end of input.

foo => <p>foo</p>
=foo => <h1>foo</h1>
==foo => <h2>foo</h2>
 ...
 
["foo"] => <blockquote>foo</blockquote>

Inlines
-------
Can appear anywhere within a block

*foo* => <strong>foo</strong>
[url,text] => <a href="url">text</a>