Moving Volume-Weighted Avg Price, % Channel, BBs

This script includes:

- Moving Volume-Weighted Average Price line.

- User-defined % band above and below, very useful for "breakout" signals, and mentally adjusting to the magnitude of price swings when viewing an automatic scale on the price axis.

- Volume-Weighted Bollinger Bands, which are more sensitive to volume.

More detail:

- This is like TV's basic VWAP in concept, except the major flaw in that is that it has reset periods that you can't override, and the volume is cumulative until the next hard reset. The 'reset' is OK for securities trading, that resets every day anyway. But not for crypto - and not if/when securities trading goes 24/7. Also, the denominator accumulating over the entire period is also *not* OK, because then what is shown means something different as the day progresses - which kind of makes it useless. In other words, it starts out very sensitive to volume, and gets progressively more numb to it as they day progresses, and starts flattening out.

- This fixes both problems, by using a user-definable moving window for the average. Essentially combining SMA with volume-weighting.

- You may also find an invaluable trading aid, in the % bands above and below.

- What can optionally be shown is standard deviation bands, aka Bollinger bands. The advantage over regular BB is that it's volume-weighted. Since it is already calculated on a moving average, the period for the standard deviation has been shortened by default, and the magnitude increased, to better approximate regular Bollinger Bands - but it's still more responsive to volume.