Pass more values to post-processing scripts

[SizzlechestSA]

It would be nice if more values would be passed to the post-processing scripts. For example, I had a need for the blackhole directory and it would be better not to have hard-coded it in the script.

[switch]

We can't pass every config value to the user-scripts.

Expanding the api to return either a requested config value, or every config value would maybe be better; currently it can return the current speedlimit.

[shypike]

Make it a global environment variable.
You can do that in Windows and I'm sure there's a way in Linux too.