Changes for #2569: DS can now work with both PySide and PyQt4.
More testing is needed to observe no more Python crash at app exit (Mac).
change the includes based on qt binding
added modified python_qt_binding package
change setup to use either Qt binding. Update instructions for installing PyQt.
modified PyQt package directory
updated README.rtf for PyQt installation.
Merge branch 'pyqt' into build