1.7.0 - Enhanced variable scrubbing and context vars

Scrub frame variables manually in case scrubbing isn't already done by zend.exception_ignore_args.

This allows for individual per-frame decissions to either drop certain variables or keep them. It doesn't change, however, how frame variables are transported to Sentry, which usually is very none-descriptive due to how Sentry handles variable repreesntation.

To add more details to variables, specific frame variables can be analyzed and copied from frames to the event context befor being potentially scrubbed and stringified.