1.7.4 released: fixes and additions (dedicated to the Free Internet)

Additions and fixes on 1.7.4 release:

= 1.7.4 =
*Release Date - 27 Jul, 2017*

* Fix woocommerce warning on WP login and WP_w3all plugin login flow code.
* Add shortcode to retrieve and display (formatted or plain text) phpBB posts (by ID), into WP posts, see https://www.axew3.com/w3/2017/07/wordpress-shortcode-phpbb-posts-into-wp-post/
* Add transfer phpBB users into WordPress (transfer option useful in some contest).
* Fix option 'Retrieve posts on Last Topics Widget based on phpBB user's permissions'.
* Fix option 'Last Posts on widget read/unread': eliminate a not needed query and add correct code to output icon read/unread in any configuration (not showed if avatars option disabled, due to a variabe lack on output code, and never reported by anyone as bug)
* Fix/Add css classes for the widget WP_w3all Login (so it is possible to style it like the Last Topics Widget) https://www.axew3.com/w3/forums/viewtopic.php?f=2&t=550#p2158.
* Fix correct URL on WP_w3all login widget, to correctly point to PM phpBB folder, when there are new PM messages and notice url link is shown.
* More minor fixes.