Tuples should render as lists

The tuple type does not exist in OpenSCAD,
but is a legal indexable object in Python that
can be exchanged for a list.

Without this patch, passing a list of tuples
or a tuple of tuples would result in invalid
OpenSCAD output.
Rotate extrude should support segments

The $fn variable is available for rotate extrude
and should be exposed via the segments kwarg.
Merge pull request #13 from ewindisch/tuple-vector

Tuples should render as lists
Merge pull request #14 from ewindisch/rotate_extrude_fn

Rotate extrude should support segments
conflict
added convenience methods for debug, disable, root, and background
Added scad_render_animated_file() to solidpython.py
Added back_and_forth argument to scad_render_animated_file()
restored some comments
Fixed bug where file_header and includes weren't getting written to animated files
own function for including solidpython code in generated scad
added unit tests for modifier convenience methods
Added animation_example.py.   Cleaned up run_all_examples.sh formatting
Added Animation section to README.md
Added test_scad_render_animated_file()
added test_scad_render_to_file()
formatting
Consolidated pyeuclid patching code into path_euclid.py
Merge branch 'develop' of https://github.com/SolidCode/SolidPython into develop