Reduce bundle size

[merceyz]

Related issues
Closes #163

Changes

• Build ESM version
• Upgrade to babel 7
• Use core-js@3
• Use clsx instead of classnames
• Add @babel/plugin-transform-runtime
• Add babel-plugin-optimize-clsx
• Add browserlist (copied from https://github.com/mui-org/material-ui/blob/80aaebc729c91d05db89ce9064effe4824214437/.browserslistrc )
• Use cross-env to fix build on Windows

Result
Bundled with rollup, excluding externals

Before	23,9 KB (24 540 bytes)
After	19,5 KB (20 050 bytes)

[iamhosseindhv]

Outdated PR. Propbably a new one takes less time than resolving conflicts on this. Thanks for your contribution @merceyz

[merceyz]

I would have had to resolve them anyways, so I did, you can re-open the PR 👍

[iamhosseindhv]

Thanks @merceyz appreciate it a lot. Happy to merge.

Can you share the setup you use to measure bundle size? (last time you mentioned rollup)
I'd like to add the repo, so from now on we can see the effect of each bit of code being added/removed.

[iamhosseindhv]

Fixed in #268 using a third party library.

Huge thanks @merceyz for your contribution. Would be my pleasure to have you in contributors list, if you could make a PR with a dummy commit.

[merceyz]

Fixed in #268 using a third party library.

Great, less code to maintain!

Would be my pleasure to have you in contributors list, if you could make a PR with a dummy commit.

Thank you but that's not necessary 👍