Merge branch 'develop' into feat/new_args_system

docs/backtesting.md

@@ -39,7 +39,7 @@ Assume you downloaded the history data from the Bittrex exchange and kept it in
 You can then use this data for backtesting as follows:
 
 ```bash
-freqtrade backtesting --datadir user_data/data/bittrex-20180101
+freqtrade --datadir user_data/data/bittrex-20180101 backtesting
 ```
 
 #### With a (custom) strategy file
@@ -72,6 +72,17 @@ The exported trades can be used for [further analysis](#further-backtest-result-
 freqtrade backtesting --export trades --export-filename=backtest_samplestrategy.json
 ```
 
+#### Supplying custom fee value
+
+Sometimes your account has certain fee rebates (fee reductions starting with a certain account size or monthly volume), which are not visible to ccxt.
+To account for this in backtesting, you can use `--fee 0.001` to supply this value to backtesting.
+This fee must be a percentage, and will be applied twice (once for trade entry, and once for trade exit).
+
+```bash
+freqtrade backtesting --fee 0.001
+```
+
+
 #### Running backtest with smaller testset by using timerange
 
 Use the `--timerange` argument to change how much of the testset you want to use.
@@ -92,12 +103,6 @@ The full timerange specification:
 - Use tickframes since 2018/01/31 till 2018/03/01 : `--timerange=20180131-20180301`
 - Use tickframes between POSIX timestamps 1527595200 1527618600:
                                                 `--timerange=1527595200-1527618600`
-- Use last 123 tickframes of data: `--timerange=-123`
-- Use first 123 tickframes of data: `--timerange=123-`
-- Use tickframes from line 123 through 456: `--timerange=123-456`
-
-!!! warning
-    Be carefull when using non-date functions - these do not allow you to specify precise dates, so if you updated the test-data it will probably use a different dataset.
 
 ## Understand the backtesting result
 
@@ -184,6 +189,7 @@ Hence, keep in mind that your performance is an integral mix of all different el
 Since backtesting lacks some detailed information about what happens within a candle, it needs to take a few assumptions:
 
 - Buys happen at open-price
+- Sell signal sells happen at open-price of the following candle
 - Low happens before high for stoploss, protecting capital first.
 - ROI sells are compared to high - but the ROI value is used (e.g. ROI = 2%, high=5% - so the sell will be at 2%)
 - Stoploss sells happen exactly at stoploss price, even if low was lower
@@ -192,6 +198,9 @@ Since backtesting lacks some detailed information about what happens within a ca
   - Low uses the adjusted stoploss (so sells with large high-low difference are backtested correctly)
 - Sell-reason does not explain if a trade was positive or negative, just what triggered the sell (this can look odd if negative ROI values are used)
 
+Taking these assumptions, backtesting tries to mirror real trading as closely as possible. However, backtesting will **never** replace running a strategy in dry-run mode.
+Also, keep in mind that past results don't guarantee future success.
+
 ### Further backtest-result analysis
 
 To further analyze your backtest results, you can [export the trades](#exporting-trades-to-file).