validation for negative values on range validator.

[joicemjoseph]

Feature Request

While validating negative integer values using range tag with ValidateStruct(), I received the following error message.
The following validator is invalid or can't be applied to the field: \"range(-1|50000)\"

I request to add support for -ve integer values for range tag.

Q	A
New Feature	yes
RFC	no
BC Break	no

Summary

If this feature is added, then we could validate -ve integer values.
the validation tag range(-1|50000) would work as expected.

If you can agree, I could work on it.

[sergeyglazyrindev]

Hello guys!
I forked this package cause owner disappeared. Hope, he will be back, but it would be easier to merge these changes back if he is back
Link to my repo: create issue there and we'll discuss it.