Implement Temp Pipelines while the user edits a pipeline.

This will help the user recover from a crash. We could set the "last temp directory used" into the user preferences file on close. Then clear the directory on quit or when a window closes. The next time the application starts, that directory pref is read from the settings, checked for any left over pipelines. If there are no pipelines, then generate a new temp directory. If there are then those pipelines should be loaded into memory with a Window title of something like "RECOVERED PIPELINE 1"