Support SplitApplyCombine.jl methods

[bencottier]

Named dims are not supported in SplitApplyCombine.jl, e.g. splitdimsview.

I haven't looked into what's required yet, I'm just assuming it can be supported in this package.

Example:

julia> using SplitApplyCombine, NamedDims

julia> M = NamedDimsArray{(:features, :observations)}([1 3; 5 7])

julia> map(x -> sum(x), splitdimsview(M, :features))
ERROR: MethodError: no method matching splitdimsview(::NamedDimsArray{(:features, :observations),Int64,2,Array{Int64,2}}, ::Symbol)
Closest candidates are:
  splitdimsview(::AbstractArray) at /Users/bencottier/.julia/packages/SplitApplyCombine/RS5bI/src/splitdims.jl:127
  splitdimsview(::AbstractArray, ::Int64) at /Users/bencottier/.julia/packages/SplitApplyCombine/RS5bI/src/splitdims.jl:129
  splitdimsview(::AbstractArray{var"#s46",N} where var"#s46", ::Tuple{Vararg{Int64,M}}) where {N, M} at /Users/bencottier/.julia/packages/SplitApplyCombine/RS5bI/src/splitdims.jl:130
Stacktrace:
 [1] top-level scope at REPL[4]:1

julia> map(x -> sum(x), splitdimsview(M, 1))
2-element Array{Int64,1}:
  4
 12

julia> map(x -> sum(x), eachslice(M; dims=:features))
2-element Array{Int64,1}:
  4
 12