Restore state when opening folders to applicable windows

Note: "clean window" is defined as 1) having an empty project and 2)
having no pane items or only empty unnamed buffers

When project is empty and there is saved state associated with the
opened/added folders...
* Open a file or folder (from command line or Open menu)
  * If we have a clean window, restore project state in window
  * If window is dirty, restore saved state in new window

src/atom-environment.coffee

@@ -1019,23 +1019,38 @@ class AtomEnvironment extends Model
   openLocations: (locations) ->
     needsProjectPaths = @project?.getPaths().length is 0
 
+    foldersToAddToProject = []
+    fileLocationsToOpen = []
+
+    pushFolderToOpen = (folder) ->
+      if folder not in foldersToAddToProject
+        foldersToAddToProject.push(folder)
+
     for {pathToOpen, initialLine, initialColumn, forceAddToWindow} in locations
       if pathToOpen? and (needsProjectPaths or forceAddToWindow)
         if fs.existsSync(pathToOpen)
-          @project.addPath(pathToOpen)
+          pushFolderToOpen @project.getDirectoryForProjectPath(pathToOpen).getPath()
         else if fs.existsSync(path.dirname(pathToOpen))
-          @project.addPath(path.dirname(pathToOpen))
+          pushFolderToOpen @project.getDirectoryForProjectPath(path.dirname(pathToOpen)).getPath()
         else
-          @project.addPath(pathToOpen)
+          pushFolderToOpen @project.getDirectoryForProjectPath(pathToOpen).getPath()
 
       unless fs.isDirectorySync(pathToOpen)
+        fileLocationsToOpen.push({pathToOpen, initialLine, initialColumn})
+
+    if foldersToAddToProject.length > 0
+      @loadState(@getStateKey(foldersToAddToProject)).then (state) =>
+        if state and needsProjectPaths # only load state if this is the first path added to the project
+          files = (location.pathToOpen for location in fileLocationsToOpen)
+          @attemptRestoreProjectStateForPaths(state, foldersToAddToProject, files)
+        else
+          @project.addPath(folder) for folder in foldersToAddToProject
+          for {pathToOpen, initialLine, initialColumn} in fileLocationsToOpen
+            @workspace?.open(pathToOpen, {initialLine, initialColumn})
+    else
+      for {pathToOpen, initialLine, initialColumn} in fileLocationsToOpen
         @workspace?.open(pathToOpen, {initialLine, initialColumn})
-
-    if needsProjectPaths
-      @loadState(@getStateKey(@project.getPaths())).then (state) =>
-        @restoreStateIntoEnvironment(state) if state
-
-    return
+      Promise.resolve(null)
 
 # Preserve this deprecation until 2.0. Sorry. Should have removed Q sooner.
 Promise.prototype.done = (callback) ->