- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
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

Fix an 11 year old mistake: Let the hash functions take a void* instead
of unsigned char* argument.

In light of the recent 2^69 operation collision-finding attack on SHA1,
add support for SHA256.

Tested on: i386, sparc64
Tested using: NIST test vectors, built-in tests
X-MFC-after: 5.4-RELEASE