Texttool

[PaulCampbell]

I added a text tool for something I needed to do (Canvas now responds to keyboard events).

Here it is...

I also added in a couple more example html files to show it working, and updated the Tools example on the docs page. You can see it working there... Quite simple to use, just add a

 <a href="#tools_sketch" data-tool="text">Text tool</a>