split up random and gridded tests into separate functions
(#387)
rework the random interpolation test to not do so many realizations, just increase number of random points
(#387)
make lensing_ps capable of working with subsample of pre-existing shear grids
(#387)
make subsampleGrid return the new grids
(#387)
making interpolation testing use strict subsample of fine grid
(#387)