Renaming current Configuration.

- Added “rename” dialog.  If the user commits, saves to disk.  Doesn’t
touch the actual configuration title unless the user commits the dialog.

- Made the dialog update the window title while the user is typing, and
revert the window title if the user cancels the dialog.

- This uses the iOS 8 version of an alert dialog.  If any of my users
are using iOS 7 or earlier, I’ll have to detect that at runtime and use
the (deprecated) UIAlertView class for that situation.  I’ll wait to do
that ’til I’ve confirmed what they’re using.

- Added more data wrappers in the main view controller, for calling
+[LMUDataManager save], getting/setting the current configuration name,
and setting the window title from that name.