Introduce a binary-safe wrapper for strlen() and use it in seems_utf8(), utf8_uri_encode(), and wp_read_image_metadata().

Use binary-safe POMO_Reader::strlen() in MO::export_to_file_handle().

fixes #28162.
Built from https://develop.svn.wordpress.org/trunk@28806

git-svn-id: http://core.svn.wordpress.org/trunk@28615 1a063a9b-81f0-0310-95a4-ce76da25c4cd

Author:    Sergey Biryukov <sergeybiryukov.ru@gmail.com>

Conflicts:
	wp-admin/includes/image.php
	wp-includes/formatting.php
	wp-includes/functions.php
	wp-includes/pomo/mo.php
Call static methods with required Namespace

Fixes #3 when using \PO generator.
Revert "Minimum stability to dev"

This reverts commit e64577a28e92088ba7a6fb1ade9551c61222d716.