SWAT editor should prompt to save before opening a new SW

[ChrisPC]

EXPECTED: If the currently open storyworld has been modified (based on undo level?), SWAT should pop up a modal dialog box asking the player if they wish to save current changes. YES opens a Save dialog box, then continues with the opening action. NO continues the opening action. CANCEL backs out of the opening action and returns to SWAT.

CURRENT: No warning or popup is displayed. SWAT simply discards any user changes and opens the newly selected storyworld.