#162 Fix a bug in linear binning which could cause very bad results for certain use cases. #176
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@vduret and @akritiasto reported some very poor accuracy in NN correlations with linear binning, which this PR fixes.
The bug was actually present for any Linear binning if the separations are given in angular units other than radians. The underlying bug was that the b parameter (used internally to determine when to split pairs of cells being considered for accumulation) did not have the angular units applied to it.
So if the separations are given in say arcsec, then it was missing a factor of Pi/(180 x 60 x 60) = 5.e-6. That's a big factor.