Parametric Fractal Trees

This is a modified version of an OpenSCAD example by Torsten Paul. With the original one, after extruding, the objects suffered of some strange gapes especially when using higher angles.

I added a few parameters and other modifications to be able to generate 3D printable fractal trees needed for a student research project. The base is parametric too and can be generated with the same parameters as the trees.

Other options:
- minimum and maximum angle of the branches
- generating random t