I've added tree growing direction so trees can be drawn growing left, up, or right as well as down. With the root-orientation code in place from revision 2017, this is just a matter of rotating a tree design about the root.
Note - there is a minor imperfection in the line from root 'a' to the single child, this is because text dots are not exactly centered yet so the 0 radian anchor is not properly at the east.
