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- support init non-singleton instance of RGeocoder to support different stream simultaneously (creating RGeocoderImpl class to support that)
- added the capability change the header columns when loading custom stream and loaded different schemas
- added query_dist to support returning distance in addtion to the reverse geocoding data itself
- added do_extract to trigger extraction for any Geonames file, e.g: 1000, 15000 etc
- removed win32 and python2 support. added utility function to load data from files/buffers