allow extensions to escaping, for example numpy types

[bcsaller]

This expects that when you extend converts you do so using the default as a base dict. I've used it as follows to include escape support for a couple of numpy types.

mysql_converters = {
numpy.int64: pymysql.converters.escape_int,
numpy.float64: pymysql.converters.escape_float,
}

[terricain]

Pretty sure encoders and decoders are dictionaries of different contents.

encoders is type -> conversion_function
decoders is mysql field bit -> conversion_function

I think what your after is extending the encoders dict so that if you do inserts with numpy objects it'll convert them to standard python ones