- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

MFC Revisions:
256549: man-page updates
256551: .Dd bump in manpage
256553: bootenv -> ROOT fix
257842: monster list of fixes
257843: minor touchup
257844: copy install log
257845: fixup to last
257872: mdoc fixup
257939: debug check
258021: MBR bootcode fixup

Reviewed by: many
Discussed on: -current
Approved by: re (hrs)

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Fix two problems:
1) if no default gateway is given the route command will fail
and the script will abort with an error leading to an endless
loop unless configuration is cancelled or changed. [1]
2) In the IPv6 case add -inet6 to not alter the legacy IP default
route.

Reported by: Oleg Ginzburg (olevole olevole.ru) [1]
Tested by: Oleg Ginzburg (olevole olevole.ru) [1]
Approved by: re (kib)

Remove TODO which is not longer needed and the default.

Write the multi step netconfig to a temporary file and only move that
to the final name if netconfig was completely finished. This fixes
reentrance problems even better than r222611.

Suggested by: nwhitehorn
Reviewed by: nwhitehorn
Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems

Contrary to the rc.conf framework, when manualy enabling IPv6 we have
to -ifdiabled ourselves.

Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems

While doing it right for current configuration, fix the entry for rc.conf
adding the missing mandatory "inet6" keyword.

Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems

Split netconfig into three parts:
- netconfig - what auto will call which in turn will check for
IPv4 and IPv6 to be available and ask the user to configure it
by calling
- netconfig_ipv4 doing DHCP and static IPv4 addresses, and
- netconfig_ipv6 doing rtsol and static IPv6 addresses,
and then checking, querying and updating resolv.conf upon return.
Both DHCP and rtsol (in the future) might update resolv.conf already so
we seed ourselves from that file if available.

Reviewed by: nwhitehorn
Sponsored by: The FreeBSD Foundation
Sponsored by: iXsystems