`portfwd-loopback-choice' was not consistently documented.
- update usage info in tools
- ack, plink is over 24 lines now
- update man pages for Unix version
- Doc changes:
- move long description from (GUI) "config" to "using"
- sorry if complete specification isn't what this section is meant for,
but if you only read "using" it was hard to find.
- ensure enough references to this made in other sections (GUI,
command-line)
- update instance of plink usage info
git-svn-id: svn://svn.tartarus.org/sgt/putty@3740
cda61777-01e9-0310-a592-
d414129be87e