Build #1338, #1343, #1348, #1349, #1350, #1358

PHPBB3-11904
Revisit ALLOW_CDN_EXPLAIN wording

PHPBB3-10174
Rename "Ban usernames" to "Ban users" in ACP

PHPBB3-11666
POST_DELETED should refer to posts instead of messages
PHPBB3-12311
Metadata Manager should require license instead of licence

PHPBB3-12315
NO_SEARCH_INDEX in language/en/acp/common.php uses invalid HTML

PHPBB3-11336
Rename mode parameter from "leaders" to something more accurate for the
"The team" page

PHPBB3-11959
List of users in notifications should be trimmed