External proxy settings should not be per-session

We've got a situation where we've been trying to run some sessions on a server recently configured with an external proxy. We discovered with some difficulty that many of the sessions were designating their own external proxy host and port settings which were different from the server's configuration.

It doesn't seem to me that an exported scraping session file should contain external proxy information, since those settings are specific to the environment a session is running in. Rather, the screen-scraper instance should be the only place where those settings are specified.

I'd like the per-session external proxy settings to be deprecated in future screen-scraper versions. If there are backwards compatibility concerns, then an alternative might be to add a screen-scraper setting to ignore per-session proxy information.