Fix type inference issues on Julia master

See JuliaLang/julia#36208

For some reason, the type returned by ManyPencilArray is correctly
inferred when `length.(stuff)` is replaced by `map(length, stuff)` in
`size_local()`.

Using `broadcast` instead of `map` also works, which is surprising given
that the dot syntax should be equivalent to broadcast.

Author: jipolanco

src/PencilArrays/pencil.jl

@@ -227,7 +227,7 @@ By default the dimensions are not permuted, i.e. they follow the logical order
 of dimensions.
 """
 size_local(p::Pencil; permute::Bool=false) =
-    length.(range_local(p, permute=permute))
+    map(length, range_local(p, permute=permute))
 
 """
     size_global(p::Pencil; permute=false)