Error if multiple modules are running simultaneously

[mr-martian]

If a module opens a new window and waits for input, it's possible for the user to start another module. However, when a module closes, it deletes ModuleManager.project, leading to an error when the other module finishes and tries to do the same.

[cdfarrow]

Need to make it essentially modal when running a module to prevent the user from doing anything in FlexTools when a module opens its own dialog.