Editorial pass through first 1/2 of IPF NAT section.

Sponsored by: iXsystems
White space fix only. Translators can ignore.

Sponsored by: iXsystems
Consistently add the trailing '/' after /pub/FreeBSD

Sponsored by:	The FreeBSD Foundation
Add ftp6.ua.freebsd.org as a mirror, it seems to service ftp/http and rsync.
cvsup didn't reply and is actually not being pushed anymore as a public
servers from our (FreeBSD) end so I didn't list it as such.

PR:		175861
Remove nonexistent ftp4.fr.FreeBSD.org.

Sponsored by:	The FreeBSD Foundation
ftp2.pl does not respond on ftp port, only http.

Sponsored by:	The FreeBSD Foundation
ftp9.tw.FreeBSD.org stopped mirroring in 2010.

Sponsored by:	The FreeBSD Foundation
ftp3.tw.FreeBSD.org is out of sync since 2008.

Sponsored by:	The FreeBSD Foundation
Remove ftp.sk and ftp2.sk.  ftp.sk requires authentication, and ftp2.sk
/pub/FreeBSD directory is empty.
While here, remove cvsup server entry.

Sponsored by:	The FreeBSD Foundation
Remove ftp10.tw, no longer mirroring FreeBSD.

Sponsored by:	The FreeBSD Foundation
Remove ftp6.de, almost 6 years out of sync.

Sponsored by:	The FreeBSD Foundation
Improve XHTML table of contents readability by reducing vertical spacing
and using slightly larger fonts for headings.

PR:		docs/186858
Submitted by:	Allan Jude <freebsd@allanjude.com>
- Merge the following from the English version:

	r43778 -> r43780	head/ja_JP.eucJP/books/handbook/cutting-edge/chapter.xml
Finish editorial pass through IPF NAT.
Comment out symbolic substitution section for now.
It is confusing as written and may no longer be needed with IPF's new syntax.

Sponsored by: iXsystems
Finish initial editorial review of IPF chapter.

Sponsored by: iXsystems
Move the IPF chapter after the IPFW chapter.

Sponsored by: iXsystems
Initial prep work for IPFW section so that it starts to match layout
of other firewall sections.
Many more commits to come.

Sponsored by: iXsystems
Start editorial review. To be continued tomorrow.

Sponsored by: iXsystems
Fix translation of release dates.

PR:		www/182877
Submitted by:	malt <malt@mailoo.org>
White space fix only. Translators can ignore.

Sponsored by: iXsystems