#2 Allows export to proceed, ignoring problematic transactions

[Matija Nalis]

attached patch against 0.3.1 allows export to proceed even if some transactions seem to have no account.

Previously, pm2qif would die without exporting anything; with this patch it will issue warning with some debug information, and continue export with such transactions ignored.

[Gareth Watts]

Thanks for the patch - tbh I'm amazed anyone is still using this tool! I haven't touched it in years