add default vector implementation

As requested by sk89q in <https://github.com/SpongePowered/Sponge/pull/29>.
This comment applys to float and double stuff.

Don't use an epsilon, use `Float`/`Double.compare(a, b) != 0`.

http://stackoverflow.com/questions/3667932/why-use-float-floattointbits-in-java-float-comparisons