Make qtpy to set the QT_API environment variable
Make qtpy to set the QT_API environment variable

- Since qtpy is just a wrapper, there's no other way to tell external
processes started by a PyQt/PySide application the Qt toolkit its parent
is running on.
- Because of this, not setting QT_API was breaking Spyder's IPython
kernels and Python consoles.

davvid/qtpy,spyder-ide/qtpy,davvid/qtpy,goanpeca/qtpy,goanpeca/qtpy