- 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)

MFH (r291198, r291260, r291261, r291375, r294325, r294335, r294563)

Remove the HPN and None cipher patches.

MFH (r263234, r263691, r266465, r290671, r290672, r290673, r290674,
r294320, r294322, r294324, r294330, r294469, r294494, r294466)

Reduce diffs to head in preparation for removing HPN and None.

Add a pre-merge script which reverts mechanical changes such as added
$FreeBSD$ tags and man page dates.

Add a post-merge script which reapplies these changes.

Run both scripts to normalize the existing code base. As a result, many
files which should have had $FreeBSD$ tags but didn't now have them.

Partly rewrite the upgrade instructions and remove the now outdated
list of tricks.