Uglify settings break library code

[dignifiedquire]

I have some crypto library code that when I include it breaks due to the very agressive uglify settings here: https://github.com/developit/preact-cli/blob/master/src/lib/webpack-config.js#L405

Once I remove the unsafe_comps and unsafe options everything works fine. I know it's nice to get smaller code but maybe it would be good to disable unsafe options by default as I suspect that there are quite a few libraries out there that will break due to these optimisations. And this is especially hard to catch as tests usually run against dev builds and not against production builds.

#56 would allow me to workaround it, but I still feel that not breaking libraries should be rather the default and unsafe optimisations should be behind a flag.

[developit]

I think we could remove those, they are unlikely having too much effect.

[lukeed]

Yeah, we can remove. But going forward, #56 should be the way to handle this or any custom settings.

[dignifiedquire]

Fixed in #144