Fcst

* Re-design the back-test functions

**Breaking changes**
* Backtesting related functions and automation function is changed to support a new and more flexible way of back-testing

* Add `EMA` in `model_list`

* Add backtest evaluation method: `eval_method` parameter in backtest and automation functions

**Breaking changes**
* Add/re-arrange function arguments

* Add reduce recursive models using `Ridge` and `GradientBoosting` from `sklearn` in `model_list`

* Add models in `model_list`

* Fix import error in `automation` module. `base_models` has been moved to `model_list`