Interpolation error

[brycefrank]

Some distortion or error is present when using the interpolation function.

Here is a plotted array before interpolation using the code:

import matplotlib.pyplot as plt
import pyfor

A = pyfor.cloud.Cloud("sample.las")
A = a_grid.array("min", "z")
plt.imshow(A);
plt.colorbar()
plt.show()

Here is a plotted array after interpolation using the code:

A = a_grid.interpolate("z", "min")
plt.imshow(A);
plt.colorbar()
plt.show()

[brycefrank]

Fixed in this commit.