[PyQt] PyQt Support for Qt5 and Raspberry Pi

[Phil Thompson]

The current PyQt4 snapshot supports the QtCore, QtGui, QtWidgets and
QtPrintSupport libraries of
Qt5-alpha. Support for the remaining classes that also appear in Qt4 will
be added soon. Both Python3 and Python2 are supported.

I don't have access to a Raspberry Pi so I would appreciate it if somebody
who does would help me work through any remaining build issues. All that's
needed at the moment is for somebody to try and build it (and the the
current SIP snapshot), run the existing examples and give me feedback.

Thanks,
Phil