[Bug] Nested code block markdown

[dantechguy]

Related to #4, in this scenario I have used a # in a block quote. First, the code block is incorrectly inside the code block, and secondly, the # is causing the code comment to become a h1 inside the code block:

> blockquote


```
code

# c

more code
```

which generates:

<blockquote>
  blockquote
  <p>  </p>
  <code>
    <code>
      <p>code  </p>
      <h1>c</h1>
      <p>more code  </p>
    </code>
  </code>
</blockquote>