Add subtitle to acp search result issues

This changes make it possible to distinguish items with the same name. The subtitle will only be displayed if search results with the same title are in the same list.
Fix typo in ImageBBCode
Merge branch '2.0'
Hide users online data list if no members are online
Add "fa-var-" less variables for all Font Awesome icons
Fix and add missing icon-related CSS classes
Fix thumbs down alt icon
Fix error handling in NewPasswordForm
Merge branch '2.0'
Rename \wcf\system\event\listener\IEventListener to IParameterizedEventListener

This is for BC reasons, as PHP does not allow using a class of another
namespace when a class with the same name already exists within the same
namespace. IParameterizedEventListener will be aliased to IEventListener
when \wcf\system\event\IEventListener is removed.

see bd8f17f01975dacba19199ac4b7f4bba567f3e98
Fix mail-reply-all icon
Fix check of $attachmentHandler object in messageFormTabs.tpl
Ignore signature setting if $showSignatureSetting is not defined
Added link to "likes" tab
Merge branch 'master' of github.com:WoltLab/WCF
Fixed inserting of quotes on init and w/ line breaks
Resetting editor did not properly revert to initial state
Updating minified JavaScript files
Preserving special characters during conversion HTML -> BBCode
Updating minified JavaScript files