automate raylib deps

[sakgoyal]

• Create a script to automatically set up raylib to avoid malicious code being committed in the repo

• move node-gyp rebuild step to postinstall so it runs after downloading raylib (automatically runs)

• npm will run install and then postinstall, in order, automatically on npm install

[sakgoyal]

this needs to manually specify curl.exe instead of just curl because microsoft did a stupid alias to Invoke-Webrequest in powershell if you type curl

[rexim]

I personally would like to go with an approach of literally vendoring the source code of raylib and building it from scratch like we do in https://github.com/tsoding/musializer