* do not display an error message "cannot connect to server" but simply "no plugin available"
* if we are on a beta/RC version, display a button to switch to test plugins compatible with Piwigo previous version
* add a tooltip with more details about the "show beta test plugins"
Implements the new general design (thanks to Clement's and Jule's mockup)
Allows the display or the hiding of non-compatible plugins
Add advanced filters in the page (harmonization with the advanced filters in the user manager)
Add the display of a screenshot, the rating and the tags for each plugins
Add Piwigo's Certification levels for each plugins
Add the file admin/themes/default/css/components/general.css to save css compnents that will be used in diffenrent places in the admin
* actions on plugins are down in AJAX (no more page reload)
* plugins can be filtered but plugins do not move from a section (active) to another (inactive)
* at the end of the upload of after a maximum duration, move the photos from the lounge to their actual categories.
* do not invalidate user cache when photos are added in the lounge, thus avoiding to rebuild cache on every photo uploaded
* the lounge system activates itself only beyond 50k (by default) photo
This algorithm does not work for Windows and when "exec" is disabled. But not having this cache size is not a major issue. What is a problem is when calculating the cache size breaks the execution, which must be avoided.
+ add a 5 minutes cache to avoid calculating cache size too often
* tested with anold PHP 5.5 (could work with earlier versions, but I prefer to not take the risk)
* piwigo.org can now tell Piwigo which version of PHP is required for each version of Piwigo. If the installed version of PHP is too old, do not let the user update.
* slight visual enhancements on the update page
* Implement new API function pwg.groups.merge
* Generalize the delete group function in admin/include/functions.php
* Implement merge action in Group Manager
* Add loading state on grouped delete in group manager
* Member manager's design fixes
* design based on Samuel's mockup + Hannah's adaptations
* on each plugin actions shown as buttons in a single column (better compatibility with verbose languages such as German)
* description always shown (no more need of the "show details" action)
* filter based on plugin title/description (javascript, no page reload)
* hide inactive plugins if they are 8 or more
* plugins no longer shown in the admin left menu, they instead get a "settings" action if relevant. Compatible with the old trigger get_admin_plugin_menu_links but new method is to simply add a "Has Setting : true" in the main.inc.php header
