• Use external links for plugins

https://github.com/glpi-project/glpi/pull/404

• New hooks: pre_show_item and post_show_item, pre_show_tab, post_show_tab

1. pre_show_item will be fired before an item is shown, ex: when viewing a ticket, change, computer,...And will be fired at each sub-item, ex: for each TicketTask, TicketFollowup, ...

2. post_show_item will be fired after the show item

3. pre_show_tab will be fired before a tab is shown (when tabs are loaded), ex: when viewing the Followup tab

4. post_show_tab will be fired after the show tab

(see file: https://github.com/pluginsGLPI/example/blob/master/inc/showtabitem.class.php to get details on parameters passed to these hooks).