Fixing isNilOrWhitespace for empty/nil strings.
Fixing isNilOrWhitespace for empty/nil strings.

`isSpace` returns false for an empty string, which is the opposite of
this method.

tulayang/Nim,singularperturbation/Nim,russpowers/Nim,haiodo/Nim,jfhg/Nim,jfhg/Nim,tulayang/Nim,mbaulch/Nim,haiodo/Nim,jfhg/Nim,singularperturbation/Nim,haiodo/Nim,tulayang/Nim,haiodo/Nim,tulayang/Nim,singularperturbation/Nim,russpowers/Nim,russpowers/Nim,russpowers/Nim,haiodo/Nim,dom96/Nim,tulayang/Nim,mbaulch/Nim,mbaulch/Nim,dom96/Nim,jfhg/Nim,singularperturbation/Nim,jfhg/Nim,singularperturbation/Nim,mbaulch/Nim,dom96/Nim,dom96/Nim,russpowers/Nim,mbaulch/Nim,russpowers/Nim,dom96/Nim,singularperturbation/Nim,russpowers/Nim,jfhg/Nim,jfhg/Nim,haiodo/Nim,mbaulch/Nim,tulayang/Nim,dom96/Nim,haiodo/Nim,dom96/Nim,singularperturbation/Nim,mbaulch/Nim