Data Filtering

By implementing the IDataFilter interface, you may now add filters to your encoders,
decoders, and data file converters. This includes a mild change to the encoder and decoder
api's.
Column data filter.

A filter which allows us to filter, or remap, the columns in our data. When provided with a list
of column names and a data row, it will output a new map that contains only the provided column
names, and any data that previously existed in those columns.
Data reader may now limit rows.

The maxRows property was added to the data decoder, in order
to limit the number of rows that are read from the file.