Distance of two random points in N dimensions
More functionalities for the classes

Comparison operations, rounding operations and matrices operations such
as trace, submatrix, minor, determinant, etc.
Physics module added.

It includes some constants and units
Simulation of a variable-length pendulum
Interactive variable-length pendulum
Physics module added
Ignore .pyc files
Geometrical definitions
Some definitions to use in graphics
r = L0 line added

Best visualization of the contraction/expansion of the spring