literal name_enable wherever possible, and ${name}_enable
when it's not, to prepare for the demise of set_rcvar().
In cases where I had to hand-edit unusual instances also
modify formatting slightly to be more uniform (and in
some cases, correct). This includes adding some $FreeBSD$
tags, and most importantly moving rcvar= to right after
name= so it's clear that one is derived from the other.
Cosmetic fixes to RC script and add support for ucarp_passfile and
ucarp_xparam.
PR: ports/148012
Submitted by: Alexey V.Degtyarev <alexey@renatasystems.org> (maintainer)
