Make Blueprint Author, Mode, & Revision available as this.x variable in the BluePrint

As Per:

I thought I would add an actual feature request.

Currently the author: tag is available for Blueprint creators. I would like to use that variable in my blueprint, but the author constant is not made available as a this.x constant.

Likewise the mode: tag that is often changed by users has been known to cause differences in the way the BP code needs to react. Having that pulled into a this.constant would also be useful.

Finally I would like to see an optional blueprint_version: tag added to Blueprints that is made available as a this.x constant. It could be used when creating MQTT Discovery variables in the code, as well as be helpful to the user base when the author updates the BluePrint helping keep things straight and preventing mix-up during support.