Turtle Art/Block graphics

Proposals how to make TurtleArt more localization friendly and more usable to kids.

* Use blocks with simple shapes - rectangulars, circles, triangles, diamonds
* Use big enough blocks so they can fit any text (e.g. Chinese uses square characters which might not fit in height on small blocks)
* Symbols + tooltips are not desirable for kids who don't have idea about functions/operators/conditions. They will lose interest if they don't know what to do.