Refactor datahandlers into their own package

freqtrade/data/history/__init__.py

@@ -6,7 +6,7 @@ Includes:
 * download data from exchange and store to disk
 """
 # flake8: noqa: F401
+from .datahandlers import get_datahandler
 from .history_utils import (convert_trades_to_ohlcv, download_data_main, get_timerange, load_data,
                             load_pair_history, refresh_backtest_ohlcv_data,
                             refresh_backtest_trades_data, refresh_data, validate_backtest_data)
-from .idatahandler import get_datahandler

freqtrade/data/history/datahandlers/__init__.py

@@ -0,0 +1,2 @@
+# flake8: noqa: F401
+from .idatahandler import IDataHandler, get_datahandler

freqtrade/data/history/history_utils.py

@@ -12,7 +12,7 @@ from freqtrade.constants import (DATETIME_PRINT_FORMAT, DEFAULT_DATAFRAME_COLUMN
 from freqtrade.data.converter import (clean_ohlcv_dataframe, convert_trades_to_ohlcv,
                                       ohlcv_to_dataframe, trades_df_remove_duplicates,
                                       trades_list_to_df)
-from freqtrade.data.history.idatahandler import IDataHandler, get_datahandler
+from freqtrade.data.history.datahandlers import IDataHandler, get_datahandler
 from freqtrade.enums import CandleType, TradingMode
 from freqtrade.exceptions import OperationalException
 from freqtrade.exchange import Exchange