Add option around FX1E behaviour

[jon-axon]

There appear to be two different behaviour in the wild for FX1E, which are mutually exclusive, yet there are examples of ROMs that require each of these to run correctly.

Apparently the original COSMAC did not alter vF during execution of this instruction, but some later interpreters set vF to either 1 or 0 depending on whether I overflows beyond normal addressable memory during the operation.

The game Spacefight 2091! relies on the latter behaviour to function correctly, however the demo Sens8tion relies on the former.

I have not seen this behaviour implemented as an option/quirk in any other interpreter, consequently other common interpreters e.g. Octo seem to only handle one form or the other (e.g. Octo doesn't render Spacefight 2091! correctly). It would be nice to implement and surface this as a configurable compatibility option in Chipolata, to allow user mandate of either behaviour.