unformatNumber for very large numbers returns negative number

[bklaric]

I'm not sure if this is related to #16, but

> unformatNumber "0.0" "1507142848002.0"
(Right -390672894.0)

For reference, the number I'm trying to parse was created by now <#> unInstant <#> unwrap <#> show.

[safareli]

it's related

[safareli]

Will close this as duplicate, thanks for reporting tho!