AdEnv does not initialize the "trigger_" data member, causing the envelope to trigger on the first call to Process ()

I am using DaisySP on the desktop to prototype code and noticed the my `AdEnv` was triggering the first time it's `Process ()` function is called. After debugging I found that `trigger_` member variable is not initialized and can have a non-zero value. I've updated my local copy to initialize `trigger_` to 0 in the `Init ()` function.