Optimizations

Two minor optimizations bring a nice 4x speed improvement.

The random number generator used internally can be passed as input

The algorithm to compute bounding balls relies on a pseudo-random number generator.
Although the algorithm returns an exact solution, it is only exact up to the epsilon
parameter. As a consequence, running the get_bounding_ball function twice on
the same input might not return exactly the same output.

This release introduces a new rng keyword parameter to the get_bounding_ball function.
It allows to define the pseudo-random number generator used internally, therefore allowing
to have repeatable outputs.

Integer coordinates fix

Accepts and process correctly integer coordinates as input, without throwing an exception.