Minimize the amount of dependencies about potree

[potree]

I think we can remove any library except mjs.
I'll look into it.

A single minimized file for would make sense for the potree source code as well in order to speed up load times.

[dkastl]

I think the original source may be with comments and using multiple files.
But then for the "production" version of the library we can setup some tool to create a minified version.

Greyhound has - as far as I could see - much less files included, so I thought Potree might not need all.

[potree]

I've removed all dependencies except for mjs.