Fix makeFileMostRecent API

Existing File Objects are opened using CMD_OPEN_AND_ADD_TO_WORKING_SET which opens the file then adds it to the working set. The act of adding it to the working set would move it to the front of the MRU list if it was the currently viewed file (which happens in step 1 of the OPEN_AND_ADD_TO_WORKING_SET command)

We create an in-memory document to edit an untitled document and call `MainViewManger._edit()` on the document object. This adds the file to the working set *before* it has been opened which, because it wasn't the current file, means that its entry got added to the end of the MRU list.

We then call `_makeFileMostRecent()` which should have made the untitled document the most recent but there was were 2 flaws:

1) It was originally intended to only reorder the working set for items added to the working set (more on this later)
2) It was getting `ACTIVE_PANE` for untitled documents which needed to be resolved to an actual `paneId`.  This is why untitled documents were MRU ordered last.  

Because `_makeFileMostRecent` was not intended to work for Temporary Files but it probably should have been otherwise you could open a temporary view in the left pane and another temporary view in the right pane and never tab between them.  You would have been scurried off to another document somewhere which would close the temporary view.  Therefore, `_makeFileMostRecent` now works on temporary views and a new event is added `Pane.viewDestroy` to trap when temporary views are destroyed so they can be removed from the MRU list.

@peterflynn