writing of dx files fails with "NotImplementedError: Only regularly spaced grids allowed"

[orbeckst]

import numpy as np
from gridData import Grid   
h, edges = np.histogramdd(np.random.random((100, 3)), bins=10)
g = Grid(h, edges)
g.export("grid.dx")

fails with NotImplementedError: Only regularly spaced grids allowed even though it should just write the dx file. This was also mentioned in MDAnalysis/mdanalysis#544 .

It's not really clear since when this is failing because that's core functionality that worked previously.