Started refactoring of FormattedText.
Removed ITextService.

Cairo renderer completely broken by this point.
More refactoring of FormattedText.
Added HitTestTextRange to FormattedText.
Added selection to TextBox.
Make mono stuff work (kinda) again.
Make Home, End and Ctrl keys work in TextBox.
Added TextWrapping setting.

TextBox doesn't handle quite a few things yet, scrolling and lines for
example.
Added licence.md

Closes #9.
Make Home key work in multi-line text boxes.
Made End key work in multi-line text boxes.
Make Up/Down arrows work in text boxes.
Replace selection in text boxes.
Don't remove selection when nothing entered.
Added mouse-select to TextBox.
Cancel TextBox selection on cursor movement.
Added syntax highlighting to intro.md
- Added Ctrl+A to select all text in the TextBox
- Made the TextBox lose its selection when focus is lost.
Merge pull request #10 from xamldude/master

Small changes to text selection for the TextBox
Inplemented double and triple click in TextBox.

Copied a load of stuff from Moonlight regarding finding next/prev word
that I've put in StringUtils.