- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

MFC r291155:
bc: sync with OpenBSD

tty.c Rev. 1.3
Avoid unintended problems with operator precedence when doing an
assignment and comparison.

bc.1, Rev. 1.31, 1.32
'.Ql Quit' -> '.Ql quit' because only the lowercase command is valid.
Clarify sentence about `quit` in BUGS section.

extern.h, Rev. 1.12
whitespace

bc.y, Rev. 1.47
Prefer setvbuf() to setlinebuf() for portability

Obtained from: OpenBSD

MFC r264573+264608+264609:

Sync with OpenBSD.

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

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

Use libedit when interacting with tty, which provided history
functionality, etc. as did by GNU bc.

This also fixes an issue where BSDL bc can not handle very long
line.

Reported by: imp
Reviewed by: imp

Replace GNU bc/dc with BSDL versions ported from OpenBSD. They have a good
compatibility level with the GNU counterparts and have shown to be mature
enough. For now, the GNU versions aren't removed from the tree, just detached
from the build.

Sponsored by: Google Summer of Code 2008
Portbuild run by: erwin
Approved by: delphij