* Replace deprecated qt functions toList() & toSet()
QSet<QString>::toList() and QStringList::toSet() are both
deprecated.
* Add back support for qt < 5.14
* distinguish between temp and cache location
* document's transident directory is created in the cache location
* add functions to access temp and cache location via Python
* 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.
