Maintenance release

Main changes

1. Introducing manually_refine_components.m for interactive component addition and removal after initialization.
2. Integration of handling 3d imaging data in various parts of the code including initialize_components.m, greedyROI.m, HALS.m, update_spatial_components.m, threshold_components.m, determine_search_location.m. Full handling of 3d imaging data is still under testing.
3. Parallel implementation of threshold_components.m and determine_search_location.m
4. Better estimation of temporal components and background when no initializer is present, e.g., when analyzing a new dataset with known spatial components.
5. The noise image is used by default as a background image, since computation of the correlation image can become very expensive when the dataset is large.