<div> should not be handle by a noop rule

[EvitanRelta]

Context

Currently, <div> are handled by a noop rule, meaning they aren't stripped but they only pass-on their converted inner-contents to their parents. They themselves don't have any markdown conversions, not even in HTML-syntax.
For example, the below 2 HTML:

<div>
  TEXT
</div>

<div aligned="center">
  TEXT
</div>

both gives the same output of:

TEXT

The problem

<div> in markdowns aren't stripped when being rendered in Github.
For example, they can be used to center images, like:

<div align=center>
  <img src="...">
</div>

Thus, they should not be converted by a noop rule.