Moving Average Envelopes

Moving Average Envelopes are percentage-based envelopes set above and
below a moving average. The moving average, which forms the base for
this indicator, can be a simple or exponential moving average. Each
envelope is then set the same percentage above or below the moving average.
This creates parallel bands that follow price action. With a moving average
as the base, Moving Average Envelopes can be used as a trend following indicator.
However, this indicator is not limited to just trend following. The envelopes
can also be used to identify overbought and oversold levels when the trend is
relatively flat.

WARNING:
- This script to change bars colors.