Makes it consistent with the WebAssembly naming conventions.

These functions act as wrappers modifying the error value of the original function into a string.

Converted the `state.rs` into an Error enum version of result.

Makes use of the `Error` enum to handle errors. This is a better way to handle errors in Rust. It is also more idiomatic.

Contains detailed information about the inner structure.

Made use of const values to store global data.
Polling is done on every tick, supposedly it's the best approach for libretro.

Added more error handling.

Added support for pyboy event conversion.

PyBoy interface was also updated with a mapping table.

Makes it easier to interact with the base py.rs file

Already working for a simple example.

Added interface to custom boot ROM loading in Python.

Using pySDL2 and sending them as part of the next frame process.
There's still many TODOs pending for performance improvements.

Also changed `save_image()` method to removed auto format append in file name.