exportDlg: Don't use native file dialog (allow event-recorded tests)
hud: Removed code that checked underMouse() for mouse clicks to allow for auto-recorded event-based testing.
(This code didn't seem to be necessary, at least not on OSX.)
view3d: Delete QVTKOpenGLWidget before app shutdown to avoid 'invalid context' error:
"QGLContext::makeCurrent: Cannot make invalid context current"
tests: Fixed import issues in lazy_test.py