Made read MMU a non mutable operation.
Added support for CPU description.
Added Display support for CPU.
Extracted type definition for `Instruction`.
Support for diag_gb!() - uses global unsafe approach, which is not problematic for the purpose.
Inline fetch() operation in cpu clock.
Moved pedantic validation up in the CPU.
Fix simple diag issue.
Changed naming of read and write unsafe ops to raw.
New pedantic asserts.
Fix an issue with HDMA destination address prevent CHIP-8 ROM from
working.

More standard support for the `BusComponent` interface.

PyBoy interface was also updated with a mapping table.

Also removed the not needed bitwise operation.

There's already two drivers implemented: Null and Print (to stdout).

The selection mode was being returned with an inverted value.