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

Handling of GameShark RAM banks differently.
Added parsing integer value errors.

Makes use of the most recent save state support in EmuKit.
Thumbnail image support.

Using static methods instead of global functions.

Faster render and better colors.

Alligned the handling with the current strategy for WASM version 1 audio flush per frame.

This reverts commit 866c2306.