Add new argument to Application::newDocument() to create a temporary
document. Also exposed to Python API App.newDocument() with a named
argument 'temp'.
The temporary document is marked with status bit 'TempDoc'. The user
will not be prompt for saving when closing. The undo/redo is disabled.
The AutoSaver skips it. And the tree view will not show it.
PropertyXLink allows linking to/from object within a temporary document
without saving.
* Fix AutoSaver inconsistent BinaryBrep setting
* Use temperary name when auto saving, so that it won't overwrite the
original file, which may cause corruption when crashing in the middel
of auto saving, especially if auto saving in a separate thread.
* Support auto recovery document containing external links
* Do not mark success after auto recover, in case the program crash
again before the user remember to save the just recovered file. Only
mark when user saves the document.
