Enable basic html support in wall text

QTextEdit box used for wall already supports limited html. It cannot do dangerous stuff like javascript but does allow basic stuff like text font and size. Allows making a nicer looking wall text with headings.

All this pull does is try to detect if html is being used and enable it by using setHtml instead of setText.

HTML support is described here: http://jay-notes.blogspot.com/2007/05/pyqt4-richtext-supported-html-subset.html

I tested with my html wall via my server @ electrum.spiderfish.net. I tried an image and background and neither were rendered. Basic font style support appeared to work fine.