Range syntax doesn't seem to work in @select macro

[davidanthoff]

The range syntax doesn't seem to work right now. For example, this throws an error:

using Query, DataFrames

df = DataFrame(a=rand(10), b=rand(10), c=rand(10), d=rand(10), e=rand(10))

df |> @select(:b : :d)

We should also add a test for the range syntax.