UNIQUE/DIFFERENCE/INTERSECT/UNION do not accept blocks containing values of type NONE! or UNSET!

[rebolbot]

Submitted by: Ch.Ensel

Unsure whether this is a bug or a feature.

>> unique [#[none]]
** Script error: none! type is not allowed here
** Where: unique
** Near: unique [none]

>> union [#[none]] []
** Script error: none! type is not allowed here
** Where: union
** Near: union [none] []

>> difference [#[none]] []
** Script error: none! type is not allowed here
** Where: difference
** Near: difference [none] []

>> intersect [#[none]] []
** Script error: none! type is not allowed here
** Where: intersect
** Near: intersect [none] []

>> unique reduce [()]
** Script error: unset! type is not allowed here
** Where: unique
** Near: unique reduce [()]

>>
>> unique [()]
** Script error: paren! type is not allowed here
** Where: unique
** Near: unique [()]

^{CC - Data [ Version: alpha 97 Type: Bug Platform: All Category: Native Reproduce: Always Fixed-in:alpha 108 ]}

[rebolbot]

Submitted by: Sunanda

This is a generalisation / more detailed variant of CC#1124

[rebolbot]

Submitted by: BrianH

A generalization of the unset! part, but the rest is a separate issue. The reason that #1124 is marked as a problem doesn't apply to the none! and paren! types.

[rebolbot]

Submitted by: Carl

Fixed. None and unset added. Paren is like block, so not added here.