AlphaDTMFiltration was failing with duplicated points

[VincentRouvreau]

Ordering changes in 3d is no longer the behaviour

Fix #72

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[mglisse]

Did you check manually on an example (without duplicated points) that it gives exactly the same filtration as before? Ok if it does.

[VincentRouvreau]

Did you check manually on an example (without duplicated points) that it gives exactly the same filtration as before? Ok if it does.

Yes, the returned simplex trees are the same for AlphaDTMFiltration() if Y = X or Y = np.array([alpha_complex.get_point(i) for i in range(N_tot)])