README update, image/signal loading streamline, etc.

[bahanonu]

• README update.
• modelGetSignalsImages - Reorganized returnType to be outside raw signals flag, so common filtering mechanism regardless of variables loaded into RAM or not. This fixes if a user loads variables into RAM then uses cross-session alignment, the viewMatchObjBtwnSessions method may not display registered images (cross-session alignment is still fine and valid).
• viewMatchObjBtwnSessions - Take out parfor in one loop that calls obj functions to eliminate serialization issues. Also change color mapping of cross session maps so that it covers the full range using the actual global IDs matched across sessions rather than diluting the range by including global IDs that don't meet the criteria. Makes the maps more colorful.
• applyImagesToMovie - Remove parallelization across inputImages to reduce memory overhead and serialization memory issues (e.g. transferring a duplicate of the movie to all workers).

[bahanonu]

Tested on Matlab 2019b, Windows 10. Merging.