Refactoring of Iterables and _ImagingCycles into Sequences.

Heavily broken at this stage, though HDF5 Sequences work.
Flake8'ed iterables.py
Adjustments to iterables.
Datasets can now be initialized with sequences.
Adjusted _align_frame for 3D frames (but still just 2D corrections)
Bug fix for indexing of Sequences
Removed auto-generated .c files from the repository.
Adapted correlation based correction for 3D.
Motion correction working except the Viterbi algorithm.
Estimation of displacements now runs, but not tested.
Frames yielded with dtype=float; fixe to align_frame
Bug fixes. Removal of atifact_channels.
Import Sequence from sequence.
iterables -> sequence
Bug fixes.
Loading sequences from dictionary.
Merge branch 'master' into 3D_SIMA
Worked on documentation.
Worked on documentation.
Add valid_roi check for 3D rois