Logarithmic quantities should support some ufuncs #6897
Description
Currently,
lq = [2,3,4,5]*u.STmag
lq - lq
# <Magnitude [ 0., 0., 0., 0.] mag>
np.subtract(lq, lq)
# UnitConversionError: Can only apply 'subtract' function to quantities with compatible dimensions
np.minimum(lq, lq)
# UnitConversionError: Can only apply 'minimum' function to quantities with compatible dimensions
A combination of the helper functions not working for logarithmic units, and the wrong helper functions being used.