[ticket/11271] Displaying in-line attached images in ATOM feed.

In-line attached images are not displaying as they are not parsing.
Included 'parse_attachments' column name for data fetching queries
in feed.php. Checked weather feeds have in-line attachments and
parsed them by using parse_attachments() method.

PHPBB3-11271
[ticket/11271] Removed in-line attachment comments properly.

Added a new regex to remove in-line attachment comments.

PHPBB3-11271
[ticket/11271] Fetched feed attachments before loop.

Fetched feed attachments before looping through feed items and
send them to method 'feed_generate_content' for each feed item.

PHPBB3-11271
[ticket/11271] Separated attachment fetching query

Removed external query used to fetch related attachments.
Added attachments fetching method with database query to
post based feed.

PHPBB3-11271
[ticket/11271] Removing unnecessary database object

Removed unnecessary global database object from 'feed_generate_content'
Method.

PHPBB3-11271
[ticket/11271] Formatting code and removing null assignment.

Formatted code and replaced null assignment with empty array
assignment to attachments parameter in method 'feed_generate_content'.

PHPBB3-11271
[ticket/11271] Changed executable bit.

Changed executable bit value from 755 to 644.

PHPBB3-11271