A vector of NamedTuple is the most basic Table. Curretly DimensionalData.jl overrides this and makes a single column table of NamedTuple.

I think this is probably never what the user would want - we should let the default behaviour come through of using getproperty on the objects of a vector rather than having a single column name.

If propertynames == () then we can use the array name as the column name.