[dev-context] Quoting problems in grph-con.lua

[Kevin Boulain]

>      \enabletrackers[sandbox]

I didn't know about that one (I was print debugging in util-sbx.lua...), thanks.

> the sandbox runner always wraps so then we also need to remove quotes in
>
>              --export-%format%=%newname%
>
> and such. (The original runners didn't do escaping.)

Yes, this exactly what I was thinking about (see first patch) and it
should address your concerns about being backward compatible too.
That's also true for the others runners in the file (but I don't know
if the parameters like %color% and %rgbprofile% relies on this
behavior).