Replace `Array{T, 1}` with `Vector{T}` and `Array{T, 2}` with `Matrix{T}`

[LilithHafner]

There are still usages of Array{T, 1} throughout the codebase. In some rare cases they are intentional but in many cases this is a holdover from very old versions of Julia. Especially in example output we should pretty much always be using Vector and Matrix rather than Array{T, 1} and Array{T, 2}.

Tagging with the docs label because it is most important to fix this for documentation and less important (if at all) to make the change in source code.