Migrate to NAPI

[extremeheat]

NAN is dependent on v8 and the node ABI, making it version dependent. It's a hassle to use prebuilds because they're tied to node versions and causes problems with Electron because NAN doesn't handle render process re-use very well.

I think looking at migrating over to NAPI would be a good idea, looks like the bindings aren't too big so it shouldn't be too much work.

the steps here could be of help, https://napi.inspiredware.com/getting-started/migration.html#Run-the-conversion-tool