A new boolean on XModuleSystem that determines whether to allow execution of untrusted unsandboxed code.

Python should have -E, not sure of a clean way to do it, but this at least only applies it to python.

Make it possible for customresponse check functions to get extra arguments, though they need to be declared in the XML.

We would fail if a global was defined with a non-jsonable value inside a jsonable one.  Now we don't/