InitGui.py: Store SiloAuthDockWidget reference on the QDockWidget to
prevent Python from garbage-collecting it while its 30-second QTimer is
still running. The lost reference caused 'QThread: Destroyed while
thread is still running' followed by abort.
ztools InitGui.py: Move addWorkbenchManipulator() call from module-level
into Initialize(), after command modules are imported. The manipulator
references ZTools_DatumCreator, ZTools_DatumManager, ZTools_EnhancedPocket,
and ZTools_RotatedLinearPattern, which don't exist until the imports run.
Also updates README.md and submodule pointers.
3e09e7c099