Allows modularity and extendability in Zippy.

Also simplified error to string conversion.

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.

Allows speedup and FPS measuring.

Allows blargg's test ROM to pass.

Clarifies the boot state handling.

Added more pedantic validations preventing simple dummy data from being loaded.

Adds unwrap() to the run_image_test() calls.

Support for some basic Python testing.
Handling of loading error with proper error propagation.

Offers instructions indicating that the dependencies should be
installed before running vcpkg build.