feat: Use production build of react in packaged app

[gmaclennan]

Currently we are using the development build of react in the packaged
app. The development build is slower, see:
https://reactjs.org/docs/optimizing-performance.html

The fix is a little complicated: Normally you would build a bundle (including React) with process.env.NODE_ENV = 'production'. However, we use webpack with target='electron-renderer' and this loads all modules as externals e.g. they are required at runtime rather than included in a single bundle. The webpack.environmentPlugin() does not set NODE_ENV for runtime, it only replaces the variable in moduels included in the bundle (react isn't included, because it is 'external').

The hacky workaround is to patch in process.env.NODE_ENV = 'production' to the output bundle from webpack. A better long-term solution might be to bundle all code for electron, which might also result in a smaller build size and faster loading (lots of require calls has an overhead, especially on slow machines with spinning disk hard drives). This would require filtering out dependencies from the packaged app which are required in the bundle.

TL;DR this change should make the app more responsive (snappier™) and should work well enough for now.

[okdistribute]

@gmaclennan Thanks for this PR! We want to keep the package-lock.json file though, unless I'm missing something. Was that a mistake? Could you add it back?

[okdistribute]

I think we want to keep package-lock.json here

[gmaclennan]

@okdistribute it's still there, I see it in the "Files changed" tab. It does have quite a few changes. I'm not sure how to install an additional module without changing it.

[okdistribute]

Sigh, package-lock.. why..