Move geo code in its own dir

src/decoder/mod.rs

@@ -478,7 +478,8 @@ impl<R: Read + Seek> Decoder<R> {
             Ok(geodir) => {
                 let ascii_params = Result::ok(self.get_tag_ascii_string(Tag::GeoAsciiParamsTag));
                 let double_params = Result::ok(self.get_tag_f64_vec(Tag::GeoDoubleParamsTag));
-                geo::parse_geo_keys(geodir, ascii_params, double_params);
+                geo::geo_key::parse_geo_keys(geodir, ascii_params, double_params);
+                // TODO: save the hashmap somewhere in this module/decoder
             }
             Err(_) => {}
         }