text: Title: Signal line implemented for TRIX instead of TSI
  Body: **Which version are you running?**
  0.3.2b0
  
  **Describe the bug**
  The signal line seems to have been implemented for TRIX instead of TSI.
  
  **Expected behavior**
  According to the definitions on investopedia for:
  TRIX: https://www.investopedia.com/terms/t/trix.asp
  TSI: https://www.investopedia.com/terms/t/tsi.asp,
  there should be a signal line for TSI and no signal line for TRIX. 
  
  The in-built indicators on TradingView also displays the expected behavior:
  ![Screenshot from 2021-07-24 14-34-01](https://user-images.githubusercontent.com/52344837/126859886-1b8049bb-4a5c-4f2f-95e4-ba8420d43940.png)
  
  **Screenshots**
  ![Screenshot from 2021-07-24 14-19-42](https://user-images.githubusercontent.com/52344837/126859523-fcc8a703-7b11-4298-8f9c-236287dabb59.png)