Handle <img> tag in HTML feeds

[pulkomandy]

It would be nice to handle &lt;img&gt; tag in feeds. Some messages come with a picture and we should display it.

Idea:

• have the text view skip some lines to have some whitespace (maybe a single line, but with a huge font)
• override the draw method of the textview to overlay the image above the whitespace

We also need to download the image.