- 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 r257378,r257400,r257402,r257440:

Add a pkg(7) manpage for bootstrap

Approved by: bapt
Approved by: re (gjb)

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

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

A cross-reference takes a man page section as well. Assume pkg(1),
based on pkg_add(1).

Fix typo in option description file (using svn move).

New build KNOB: WITHOUT_PKGBOOTSTRAP to condition building of usr.sbin/pkg
Do not condition usr.sbin/pkg building on WITHOUT_PKGTOOLS anymore, so that users can
remove the old pkg_* tools without removing the pkgng boostrap

Approved by: des (mentor)
MFC after: 1 month