Directly use cpythons errors.c file

[corona10]

Accoring to #1100 I change some files.

[undingen]

oh wow that fast fast, thanks for working on this :-)
I think we don't need the declarations inside the errors.cpp file they should already be declared inside the pyerrors.h header.
And I noticed that there is a small difference inside the PyErr_NormalizeException function please copy the change over to the new errors.c file (but in a separate commit so that we have the original version as the first commit and the changes to the file in another one)
Thanks!

[corona10]

@undingen Thanks. I fix them as you reviewed.

[undingen]

thanks for the patch!