Better handling of commenting out top-level definition implementation

[avh4]

Example input:

getActiveChildren node =
    []
    -- node.children |> List.filter isActive

Current output:

getActiveChildren node =
    []



--node.children |> List.filter isActive

Desired output:

The commented-out code should remain near the function it belongs to.

TBD

• do some editors put the -- in column zero when commenting out?
• should this be determined by indentation? or by line number?
• is fixing this for top-level definitions enough, or does a similar problem apply to let/case/if/other expressions?