- 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

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

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

Sync with OpenBSD, primarily better signal and terminal handling.

Obtained from: OpenBSD
MFC after: 2 weeks

Define the size_t type since readpassphrase(3) requires it in its
definition and sys/types.h is not listed within the synopsis of the man
page.

MFC after: 1 week

Synch with OpenBSD (style).

Introduce readpassphrase(3), a superset of getpass(3). This
comes originally from Todd Miller.

Obtained from: OpenBSD