.volume() isn't documented for the Video library

[REAS]

https://github.com/processing/processing-video/issues/58

[codeanticode]

Thanks. There are a few additional functions that I included after user request: https://github.com/processing/processing-video/pull/29

In Movie, these new functions are:

• isPlaying()
• isStopped()
• isLooping()

In Capture, there is only isCapturing(), equivalent to isPlaying()

Also, after going through several issues where people tried to capture video from specialized hardware, I started incorporating support for custom pipelines in the Capture class. This new example demonstrates how it would work. I think is a simple way to support edge capture cases without need of new API.