Support for both PyQt4 and PyQt5
This release (v0.1.1) adds support for both PyQt4 and PyQt5. By default, it will first try to use PyQt4, and if that fails to import, it will try to use PyQt5. If you'd like to force PyDM to use one or the other, you can set an environment variable named PYDM_QT_LIB to either 'PyQt4' or 'PyQt5'. If you force a particular PyQt version, you will also have to force pyqtgraph to use the same version as PyDM, which you can do with its own environment variable: PYQTGRAPH_QT_LIB.