Due to lodash's packaging mechanism, it is unable to treeshake unless
you always import from it in a certain fashion. This commit adds a babel
plugin to rewrite these imports for us.
Landscape is not localised in any fashion and we never change the
default locale. As such, the locales that moment.js includes in the
bundle are redundant and can be removed
Source maps have never worked correctly on production builds, and the
way that they are bundled into the JS itself negatively impacts our time
to first paint. As such, we disable them for a significant bundle size
improvement (10MB -> 2.4MB)
Also fixes a longstanding bug where the compiled JS would be written
twice to the same file, causing the bundle to be twice as large as it
needs to be.
