Functional interface overhaul

[Speiger]

Since this is technically a recreation of FastUtil, this means I also copied some of its flaws.
The functional interface part of Primitive Collections is kinda a mess.

When I copied and redesigned it to be less clutter (I removed a lot of functions FastUtil had) I still left the messy design in it.
To give a example.

Primitive Collections adds Consumers, but not ObjectConsumers since java has them already, but IntConsumers exist and extend of javas IntConsumer.
Also imports of Javas Consumer is a special case that needs to be accounted for.
Functions duplicate for some cases because there exists 2 consumers.

And Function.class has the same problem where it has already duplicates and the function also renames the function you are going to call or delegates it. Just for the Map Interface which extends it.

For this the whole Functional interfaces kinda need a major overhaul.

This only breaks code if you specifically use said functional interfaces directly. Not even in lambdas or method references.
And maps are free from that too.

While I don't have right now no real solution for that. This needs to be addressed.
Preferably with the next minor release. (Since I treat them as Major releases until 1.0)