Abstracted a lot of drawing code and fixed invalid context warnings
Subclass UILabel instead of UIView. Updated link interaction handling

A huge amount of the code has been rewritten and made similar to
TTTAttributedLabel, with some notable changes to its behaviour.

Firstly, MDHTMLLabel is now a subclass of UILabel instead of UIView
giving you access to all of UILabel's properties and some additional
ones. However, instead of setting the text property to style the text
using the HTML tags contained it, you must now use the htmlText
property.

As well as this, all link attributes now use either NSAttributedString
attribute names or Core Text ones (e.g. NSForegroundColorAttributeName
and kCTForegroundColorAttributeName. The selectedLinkAttributes property
has been renamed to activeLinkAttributes and there is a new property,
inactiveLinkAttributes for iOS 7 when the tint color changes.

Finally, link interation now makes use UIResponder events instead
of adding buttons. This is one of a few changes made to improve overall
performance.

All additional properites are fully documented inside the header file.
There's also more comments inside the implementation
Updated README and screenshot