Add support for Decimal parsing in protocol.py

[lukeweber]

Currently a Decimal when queried from MySQLCursorPrepared is returned as a bytearray. The api states that the values FieldType.DECIMAL, FieldType.NEWDECIMAL are just a char array which I guess is why it's parsed by the string parser already.

I haven't tested the encoding on py2 but wanted feedback on whether this is a fix that would be included. I can add support/test if this seems reasonable.

It seem appropriate to convert these to Decimal here because the code notes that this should be done.

    def _row_to_python(self, rowdata, desc=None):
        """Convert row data from MySQL to Python types

        The conversion is done while reading binary data in the
        protocol module.
        """
        pass

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[lukeweber]

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Please make sure to include your MySQL bug system user (email) in the returned form.
Thanks

Done

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[lukeweber]

I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.

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