Ferjerez Space Cities Easy-print Modification

This is a customization of Ferjerez's amazing "Space Cities Generator" and "Sci-Fi City Builder". I have made a few changes to the OpenSCAD code, to improve print-ability and give smoother surfaces.

Here's a summary of the changes:

-Legs are made slightly thicker on very small towers, this makes them stronger and smoother by allowing a reasonable extrusion length on each layer. The larger towers are not changed. (See comparison photo, sliced with Simplify3D.)

-Thickness is increased in