better output for browsers

[paulovieira]

This module is fantastic! Thanks for sharing it. However I had some minor packaging problems when using it with webpack (in the context of a sapper application, as I mentioned in #4 ), namely:

• the browser output still has a reference to require('fs') (which causes problems)
• when installing from npm, we only get the output for node (but with tools like sveltekit/sapper/next, the same module can be used both in the server and in the browser)

I forked the repository to solve those problems: https://github.com/paulovieira/fast-toml/tree/umd

It's all small changes. If you're interested in merging them please let me know and I can make another PR.

Thanks.