audio/soundconverter: pass on maintainership and clean up port

• Pass maintainer from ports@ to submitter
• Add maintainer mirror to MASTER_SITES
• Add NO_ARCH
• Sort USES (portlint)
• Remove unconditional gettext USES and add NLS knob (portlint)
• Update WWW link and update pkg-descr based on upstream verbiage

PR: 200505
Submitted by: Chris Hutchinson <portmaster@bsdforge.com> (with changes)