Add MissingValues option to Infer and InferImplicitCasting

[danielfireman]

Currently, Infer and InferImplicitCasting only receive a table as a parameter, but there are some other important inputs, for instance, missingValues.

As an example, please take a look at the Schema and Configuration section our the Readme. When the "N/A" is used as missingValue, the algorithm cannot properly detect the integer type. So my first suggestion would be to follow the functional options approach, which was already used in csv.NewTable.