Add persistence across Matlab restarts
Add transaction capability in state saving
Add tests

Actions
 - load # Load a given path into the state file and the matlab path and do savepath(), atomically
 - unload # opposite of load
 - status # show all loaded paths, mimicing the order they are added to the matlab path, if project file is present, show which paths are active
 - checkin # load all paths in a project file
 - checkout # unload all paths in a project file
 - clear # unload all paths, should return the matlab path to the way it was before any loads.