Support one or more, and zero or more for slice options

[macfisherman]

From Getopt::Long:

It is also possible to specify the minimal and maximal number of arguments an option takes. foo=s{2,4} indicates an option that takes at least two and at most 4 arguments. foo=s{1,} indicates one or more values; foo:s{,} indicates zero or more option values.

[DavidGamba]

For the 1 or more I normally define 1, 99. Since go is strongly typed I wouldn't want to change the max definition to any other type than int, so defining your arbitrarily large value should do it.

For the zero or more, could you provide an example of how you want to use it in practice?