- 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 r257138:

Switch the default mtree to nmtree our new NetBSD derived mtree.

Exp-runs by: bdrewery (ports/182438)
Sponsored by: DARPA/AFRL
Approved by: re (gjb)

Switch the default mtree to nmtree our new NetBSD derived mtree.

Exp-run by: bdrewery
MFC after: 3 days
Sponsored by: DARPA/AFRL

Remember the . in .\" in the WITH_NMTREE file and regenerate the output.

Reported by: joeld

Always install our mtree as /usr/sbin/fmtree and link it as
/usr/sbin/mtree by default.

Add a src.conf option WITH_NMTREE that causes NetBSD's mtree to be linked
as /usr/sbin/mtree as well as /usr/sbin/nmtree.