Reorganize files, complete Kotlin extensions

[Peanuuutz]

Also fixed some bugs, see changes in those java files.

I'm thinking about splitting kotlin extensions to an individual artifact, because they're too large.

[httpdigest]

Thanks a lot for your work!

[tmvkrpxl0]

Speaking of which, should there be iterator support?

for(element in vector4f) {
//...
}

// Or
vector4f.forEach { element -> 
// ...
}

Class Vector4f already has method get(int component), which allows treating vectors as fixed length array.

[Peanuuutz]

Speaking of which, should there be iterator support?
...

This could be a core feature, not just for Kotlin users. Please open another issue if you will.