Changed to use generics

[vertoforce]

Just playing around with how this would look if it used the new go generics.

Of course you lose some functionality in the ability to store anything, but in some cases it's nice to return the exact type you are expecting.

Not requesting this to be merged in, just posting.

[vertoforce]

I made a new struct just to make this backwards compatible.
The only thing that isn't backwards compatible, is that now the methods return pointers instead of just interface{}