EMA and EMA Spread study

Based on initial setup from rludvik (tradingview.com/script/t9Ez6VPe-EMA-and-SMA-Spread/)

- Focussed on EMA for this script
- Added the ema as input parameters, so updating the pinescript everytime isn't needed
- also added a second ema to it, to make it easier to study/compare 2 sets of emaspread

I will publish this open, if you make your own improved version of it, please let me know :-)