Add better react and react-native compatibility

[ragibkl]

Hi maintainers,

I'm trying to integrate this library into my react and react-native projects.
I believe, the following small changes will help:

• add buffer dependency, and polyfill global Buffer
• add process dependency, and minimally polyfill global process
• add browserify-zlib dependency for browser type environment
• add react-zlib-js dependency for react-native type environment

[linuxwolf]

Thanks for the contribution!

It looks just about ready to go. I have a couple of things I'd like you to check, and one change to back out for now (we'll take care of it in a follow-up PR).

[linuxwolf]

Thanks for all the changes. I'm happy to merge as-is, but will finish this tomorrow morning (Americas) to give time for last-minute changes.

[ragibkl]

Hi @linuxwolf ,

I don't have any other changes for this PR for now. However, after more testing in react-native, I realised that I was getting invalid results.

I would like to help address that separately, and have created another PR for that.