Because Python code cannot catch and rethrow c++ exceptions
without losing context, we end up getting unknown exceptions
caught by c++ from python code (phew!).
So if we catch a python exception from processing, throw it
into the log so at least there's the full debugging detail
available on the console.
(Not ideal. Would love to see a PR allowing the full error
message to be passed correctly between c++/python/back again)
* detect SIP version to add DefaultDocstringSignature directive
SIP doesn't handle any kind of preprocessing, so there's no better solution than configuring the SIP files from CMake.
SIP 4.19.7+ supports %DefaultDocstringSignature to prepend auto-generated Python signature to existing Docstrings
