Revert "remove joint/separable out of master branch"

This reverts commit 1d999bc56ea5a4abc177a40648e1033c6a6a34a0.
Merge commit 'origin/master' into joint_audio
fix mult signals bug in joint
Merge branch 'master' into joint_audio
wavelet_1d gives absolute res, not relative - update joint_layer
Merge branch 'master' into joint_audio
fix bug for length(psi_mask)==1
make func_output take multiple outputs
Merge branch 'master' into joint_audio
make joint_tf_wavelet_factory take M in scat_opt
Merge branch 'joint_audio' of github.com:scatnet/scatnet