Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

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

Comments fixing
1) Back out "month names" -> "months names" and fix few such cases which
are wrong initially
2) "weekdays names" -> "weekday names"

Noted by: des [1]

Comments fixing
"month names" -> "months names"
typo
"Long months names (alternative)" or "in alternative form" ->
"(without case ending)"
"Long months names" -> "Long months names (as in a date)"
to not confuse developers on what purpose those sections are

Fix long months standard form

PR: 32120
Submitted by: Basileios Anastasatos <B.Anastasatos@MyRealBox.com>

Replace %y with %Y

Convert to new locale format with md_order and without E[Ff]_fmt
Add ampm_fmt to all locales

Add Greek support

PR: 24324
Submitted by: past@netmode.ntua.gr