BRK and COP now push the correct return address on the stack.
MEM_read will now take a qualifier parameter indicating the type of read (plain-data, vector, or instruction fetch), thus emulating a 6502's _VP and _SYNC pins. If you need to decode VDA and VPA from this, you can use a simple table lookup.
While this breaks backward compatibility, the fact that virtually nobody else is using the library to my knowledge gives me the dictatorial freedom to impose the superior API change.
