graphics/viewnior: update 1.6 -> 1.7, submitter becomes maintainer

PR: 243529, 243726
Submitted by: Nuno Teixeira <ed.arrakis@gmail.com>
Approved by: portmaster@BSDforge.com (maintainer timeout)
Relnotes: https://github.com/hellosiyan/Viewnior/blob/master/NEWS