format_error should return locations as a list of {"line", "column"}

[ktosiek]

Fix for #61. This way a simple json.dumps() of format_error(...) should generate correct locations.

I've left GraphQLError.__eq__ as is, but maybe it should compare dicts to self.formatted?

[Cito]

Thank you for sending the PR.

Maybe we should add an __eq__ method to SourceLocation that would also allow comparison with a dict (similar to the __eq__ method of GraphQLError). And while being at it, we could also add a custom @property formatted(): return dict(line=self.line, column=self.column) to SourceLocation that would return an ordinary dict and could be used in format_error.

[ktosiek]

codecov doesn't like the SourceLocation.__ne__ method being untested. Should I add explicit tests for __eq__ and __ne__?

[Cito]

codecov doesn't like the SourceLocation.__ne__ method being untested. Should I add explicit tests for __eq__ and __ne__?

Thtat should do no harm :)

[Cito]

Thank you!