text: Title: Issue with reults of rma moving average
  Body: **Describe the bug**
  ta.rma() should behave exactly like ta.ema() - with the only difference being the weighting factor.
  Implementation of ta.rma() in pandas_ta calculates the starting value differently than the implementation of ta.ema()
  specifically, **the first value** in the ta.rma() result should be a SMA() average of the period. If the first value is different, the whole series is different...
  
  **To Reproduce**
  ```python
  df = pd.DataFrame({'close': [1.0,0,-1,0,2,-3,4,5,-8,7,8,9,10,-5,10,0]})
  df["rma"]=df.ta.rma(close=df["close"], length=4)
  df["ema"]=df.ta.ema(close=df["close"], length=4)
  ```
  the first value that is not a NaN should be the same for both rma() and ema() - but it is not...