PyOxidizer support

[jayvdb]

PyX currently fails quite badly when added to a PyOxidizer project, initially because of indygreg/PyOxidizer#69 .

It would be a big start if the use of __file__ can be removed, or its absence ignored, or at least delayed and only used when necessary, so that the majority of PyX can work while other parts remain broken.

The initial problem I encountered was that pyxrc is always loaded from local , so any pyxrc stored inside the binary is not used.

[joerg-lehmann]

Sorry for the late response.

As suggested, in a first step commit 00d4495 removes the usage of file or make it optional.

[joerg-lehmann]

For the pyxrc issue, more investigations would be needed. Could you please provide us with more input.