Resolve "Implement a copy function"

Closes #19 (closed)

\approve @tara @ds

databaselib/database.py

@@ -167,6 +167,9 @@ class SpatiaLiteDatabase(AbstractDatabase):
 
         return version.parse(sqlite3.sqlite_version) >= version.parse(requested_version)
 
+    def __copy__(self):
+        return SpatiaLiteDatabase(self.database_filepath, self.spatialite_filepath)
+
 
 class PostGISDatabase(AbstractDatabase):
     """
@@ -276,3 +279,14 @@ class PostGISDatabase(AbstractDatabase):
             cursor.execute(sql_statement)
             for result in cursor:
                 yield result
+
+    def __copy__(self):
+        return PostGISDatabase(
+            self.host,
+            self.dbname,
+            self.port,
+            self.username,
+            self.password,
+            self.timeout,
+            self.itersize,
+        )