Growing Input Bar and Easier Markup

I have brought over the logic from iOS where the input area will grow as you add content to it. In addition to  being a much better use of space (and modern), this should improve accessibility for people who default to a font size that is bigger than the standard font as the input area should adjust appropriately.   Another useful side effect is if you decide to drag and drop an image. The mark up button is now a lot easier to see and use.