Validation needs a better way to specify '_empty_rules'

[enov]

See Redmine issue R3552 http://dev.kohanaframework.org/issues/3552

[rjd22]

@enov I really dislike the syntax of the proposed methods in the red mine issues. The syntax will result into magic variables like null and true that don't convey meaning.

[enov]

Hey @rjd22, frankly, I have not yet looked into that issue 😄 I just created this Github issue, so that we won't forget about it. One of its duplicates was one of the issues reported for version 3.2.3 in Redmine that were not fixed in version 3.3.3, and it was marked as wontfix