Black boxing encoding errors

[Douglas G. Moore]

From a discussion with @jakehanson, we realize that inform_black_box could result in integer overflow in some pathological situations. For example, if the user tries to encode the state of a 32-node boolean network with history length 1, and future length 0, the resulting encoded state will almost necessarily overflow a signed 32-bit integer.

There isn't much we can do about this aside from checking, based on the function parameters, whether we are in such a pathological situation and return an INFORM_EENCODE error.