Restore files per project

[mpeterson2]

Currently, if you open a project and switch projects, you will get all the files you were just working on. This is probably not the most useful way to go about it. It would be nice to have it so that if the user opens a different project, that project should be restored to its previous state.

This may require saving more information. From what I'm thinking now, the saved json could contain an map of objects with the key of its directory path and its values will contain what is currently being stored. It would probably end up looking like this:

{
  'path/to/project': {
    files: [
    ],
  },
  'path/2/projec2t': {
    files: [
    ]
  }
}

[mpeterson2]

Another (easier to do) thought would be to have them saved in separate files. The path could be packageDirs/save-session/projects/path/to/project. Then the file wouldn't have to be read every time we want to save it. It could just be overwritten like it currently is.

It should be done this way.