New version of indexMovie. Not backwards compatible.

Indexmovie now stores data such that all frames for one pixel can be
extracted very fast. This means that traces can be loaded from disk with
minimal delay during selectCells or extractROIs. See file for details on
how to use the new format. Use the method mat2binInd to quickly convert
a linear index into an nRows-by-nCols frame into corresponding indices
into the binary movie file.
Store movie sizes during motion correction.

Movie dimensions are now stored during motion correction. Old
acquisition2p-objects lacking this information can be updated using the
addMovieSizes function.
Updated extractRois for new binary movie files.

Use extractROIsBin with binary movie files, or extractROIsTIFF for tiff
files. The old extractROIs was renamed into extractROIsOld for use with
existing binary files. This means that code still using the old bin file
will be automatically broken (no mor extractROIs function) so that the
spots that need to be updated can be found quickly.
Added aux function to calculate a nice overview image based on pixel-pixel covariance.

This image indicates which pixels belong to active cells.