[ticket/10308] disable retain/ delete posts option when deleting a user

When deleting a user, it asks whether the posts by user should be retained
or deleted. The selection should be disable if the user has no posts.

PHPBB3-10308
[ticket/10308] Displays message to user if there are no posts.

While deletng the user, if the user has no posts in addition to the
options being disabled an added message is displayed.

PHPBB3-10308
[ticket/10308] fixes language entity.

Language key has been changed and has been made more specific to
avoid conflicts

PHPBB3-10308
[ticket/10308] fix language and user's total posts

language modified to be clear and select box disappears in case no
posts by user. user's total posts are fetched using a new query.

PHPBB3-10308
[ticket/10308] renames language key to USER_NO_POSTS_DELETE

language key renamed to make its usability more clearer.

PHPBB3-10308
[ticket/10308] fixes user deletion if no posts

introduces a hidden input field with retain posts as the mode in case
user has no posts.

PHPBB3-10308
[ticket/10308] fixes sql query, limit it to 1

instead of fetching all posts by user we limit the query to 1 to check if
a user has posts or not

PHPBB3-10308
[ticket/10308] makes variable boolean

makes user_row['user_has_posts'] boolean instead of 1 or 0.

PHPBB3-10308
[ticket/10308] fixes language variable name

Language variable has be renamed for better understanding

PHPBB3-10308
[ticket/10308] fixes indentation

indentation is fixed and user_posts variable is compared as a boolean
variable.

PHPBB3-10308
[ticket/10908] Download files only up to max_upload_filesize if limit is 0

PHPBB3-10908
[ticket/10913] Redirect to index if session id is required but was not sent

PHPBB3-10913
[ticket/10908] Document that 0 filesize configuration means limited by PHP

PHPBB3-10908
Merge remote-tracking branch 'github-dhruv/ticket/10308' into develop

By Dhruv Goel
via Dhruv Goel
* github-dhruv/ticket/10308:
  [ticket/10308] fixes indentation
  [ticket/10308] fixes language variable name
  [ticket/10308] makes variable boolean
  [ticket/10308] fixes sql query, limit it to 1
  [ticket/10308] fixes user deletion if no posts
  [ticket/10308] renames language key to USER_NO_POSTS_DELETE
  [ticket/10308] fix language and user's total posts
  [ticket/10308] fixes language entity.
  [ticket/10308] Displays message to user if there are no posts.
  [ticket/10308] disable retain/ delete posts option when deleting a user
Merge remote-tracking branch 'github-dhruv/ticket/10308' into develop-olympus

By Dhruv Goel
via Dhruv Goel
* github-dhruv/ticket/10308:
  [ticket/10308] fixes indentation
  [ticket/10308] fixes language variable name
  [ticket/10308] makes variable boolean
  [ticket/10308] fixes sql query, limit it to 1
  [ticket/10308] fixes user deletion if no posts
  [ticket/10308] renames language key to USER_NO_POSTS_DELETE
  [ticket/10308] fix language and user's total posts
  [ticket/10308] fixes language entity.
  [ticket/10308] Displays message to user if there are no posts.
  [ticket/10308] disable retain/ delete posts option when deleting a user
Merge branch 'develop-olympus' into develop
Merge branch 'naderman/ticket/10913' into develop-olympus
Merge branch 'develop-olympus' into develop

Conflicts:
	phpBB/includes/session.php
Merge remote-tracking branch 'naderman/ticket/10908' into develop-olympus

* naderman/ticket/10908:
  [ticket/10908] Document that 0 filesize configuration means limited by PHP
  [ticket/10908] Download files only up to max_upload_filesize if limit is 0
Merge branch 'develop-olympus' into develop

* develop-olympus:
  [ticket/10908] Document that 0 filesize configuration means limited by PHP
  [ticket/10908] Download files only up to max_upload_filesize if limit is 0