Using NODE_ENV to determine if frontend code should be included in the build.

Fixes issue with zip file handling.

Making use of the newly added `buildRomData()` method.

Making use of the newly added `buildRomData()` method.

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

Done that by making use of the new emukit features.

The new event driven strategy works better with react.