dx,dy,dz don't support ranges

using the dx,dy and dz argument selectors does not allow ranges. EDIT: after more testing, I have realized I cannot get the dx,dy,dz selectors to function at all, although they parse

I have realized that there are two different ways you could implement the ranges, signed and unsigned. Unsigned ranges are more intuitive

A signed range would be e.g. @e[dy=-3..7], for 3 blocks below and 7 above, an unsigned range would only allow comparing absolute distance.

Having signed ranges and some way to have range unions (and maybe negations) would be the most powerful way to resolve this