Clean up some i18n errors
* s/echo esc_html__/esc_html_e/
* Fix up logging output (escaping, no early return, etc.)
renamed:    includes/class-wp-xml-client.php -> includes/class-syndication-wp-xml-client.php
Fix interface require for XML client
Remove "WordPress" from the label for the pull clients since they can handle non-WordPress RSS and XML too.