Minimized shifts between planes during frame alignment.
Made shifts non-negative.
Support for frame-wise displacements.
Fixed depricated operation.
tweaks to ROI.py, updated doctests and unittests for ROI
Merge branch '3D_SIMA' of github.com:losonczylab/sima into 3D_SIMA
ImagingDataset doc fix
Sequnces debugging and doctests
Merge branch '3D_SIMA' of github.com:losonczylab/sima into 3D_SIMA
Added import of Sequence to doctests
More testing & debugging of Sequence objects.
Fixed test_imaging.py for 3D
Functionality to create Sequence from numpy array.
Adjusted test_motion.py for 3D.

One test case still fails suggesting a bug in HMM motion correction.
preliminary work on 3D ROI Buddy
Fixed bug in estimating pixel gains for motion correction.
Fixed _Sequence_HDF5 bug
Marked test cases known to fail.
Merge branch '3D_SIMA' of github.com:losonczylab/sima into 3D_SIMA

Conflicts:
	sima/motion.py