Bollinger Bands Width with Alerts

Standard Bollinger Band Width indicator with some convenience alerts -- please only use these alerts in conjunction with the alert-type "Once per Bar Close" in order to avoid premature (false) signals!

Alerts provided:

- bbw has rounded (started to decrease after period of rising)
- bbw has started rising (after a period of falling)

Many thanks again to J. Bollinger for his indicators and efforts in education.