FREESCAPE: CPC sounds are not implemented

[neuromancer]

CPC sounds in all the freescape are not implemented. A workaround, available only for Driller, is the use of DOS prerecorded sounds (which can be very different in some cases). Implementing CPC sounds for all the games will require to use have ay-3891x emulation, since the pc speaker is not enough.

A possible code to use is here: ​https://github.com/floooh/chips/blob/master/chips/ay38910.h (header only, no dependencies)

To correctly call the ay3891x emulated functions from the CPC registers, we can see an example here:

​https://github.com/floooh/chips/blob/master/systems/cpc.h#L471-L491

[sev-]

This is not a release blocker