bk: parallel expansion slot and carts

[shattered]

No description provided.

[cuavas]

This doesn’t meet basic standards:

• The device descriptions are far too generic, e.g. “Printer Interface” is completely unsuitable when these are globally identifying names across all of MAME.
• Superfluous semicolons on inline functions.
• Cold member functions not marked cold.
• Directly #including sound.h from headers for some weird reason (you’re supposed to get it via emu.h).
• Headers #include stuff only needed in implementation (e.g. speaker.h).
• Device classes declared in headers when they realistically will only be accessed through interfaces.
• bk_covox_device::m_data seems to be completely unnecessary – leftover copy/paste from loopback device?
• Unnecessary overridden member functions that just slow down compilation (e.g. all the empty device_reset).
• Useless #define VERBOSE 0 in files that don’t have any logging and don’t even #include "logmacro.h" – this will confuse people looking for the additional logging switching it to 1 should enable.

I’m not cleaning this one up myself. I’m sick of people just assuming I’ll do it. If it isn’t cleaned up tomorrow, I’m reverting it.

[rb6502]

@shattered You got this?