fast marching method extension (Python 3)

 This module implements the fast marching method, used to model the
 evolution of boundaries and interfaces in a variety of application areas.
 More specifically, the fast marching method is a numerical technique for
 finding approximate solutions to boundary value problems of the Eikonal
 equation:
 .
 F(x) | grad T(x) | = 1
 .
 Typically, such a problem describes the evolution of a closed curve as
 a function of time T with speed F(x)>0 in the normal direction at a
 point x on the curve. The speed function is specified, and the time at
 which the contour crosses a point x is obtained by solving the
 equation.
 .
 scikit-fmm provides functions to calculate the signed distance and travel
 time to an interface described by the zero contour of the input array phi.