Merge #9190: qt: Plug many memory leaks
ed998ea qt: Avoid OpenSSL certstore-related memory leak (Wladimir J. van der Laan)
5204598 qt: Avoid shutdownwindow-related memory leak (Wladimir J. van der Laan)
e4f126a qt: Avoid splash-screen related memory leak (Wladimir J. van der Laan)
693384e qt: Prevent thread/memory leak on exiting RPCConsole (Wladimir J. van der Laan)
47db075 qt: Plug many memory leaks (Wladimir J. van der Laan)