FloatEq impls over slices

[jtempest]

There are now FloatEqAll implementations for the *_all checks over slices, but the FloatEq checks are missing. This is because the current trait specification requires that the Epsilon type be something along the lines of [A::Epsilon], which results in errors about the type not being tagged as Sized. Assuming it is possible to implement structured epsilon checks at all, this will need to be solved in terms of defining the impls, or the traits may need to change to accommodate it.

[jtempest]

Full slice trait impls now in, commit: 1ce78ad