Add python-pyqt5 as dependency to pyqtgraph

[Fabian Binz]

Hello,

python-pyqtgraph also works with the python-pyqt5 bindings. Could you 
add the packages

python-pyqt5
pyhton-pyqt5.qtopengl

as alternative dependencies to python-qt4 and python-qt4-gl?

Best regards,
Fabian