NumPy 1.20 has been released

Indeed, it just extends `where` to the wrappers around ufunc reductions (`np.logical_and.reduce` and `np.logical_or.reduce` in this case), really remedying an oversight from when I implemented `where` for reductions... I think the advantage is clearer for taking the mean, etc. For `any` and `all`, what would be nice is to have proper short-circuiting, but that is still on the wish list.

p.s. What makes `ndarray` so particularly nice is how it deals with strides to allow views of many forms into the array. This is nicely described in the "array programming with numpy" article; see https://ui.adsabs.harvard.edu/abs/2020Natur.585..357H/abs...