implement proper avatar handling

[craigh]

• Add avatar display method to Profile interface
  • Update places using the old Smarty plugin
    • system/UsersModule/Controller/LiveSearchController.php
    • system/UsersModule/Twig/Extension/ProfileExtension.php
  • Review/extend modvars (ProfileConstant class, still used from Users module)
  • Finish implementation in ProfileModuleBridge
• Update avatar display within Profile module
  • Twig extension
  • Profile/display.html.twig
  • Hook/display.html.twig
  • Block/featuredUser.html.twig
• Reenable avatar editing
  • Update Zikula.Profile.Avatar.js
• Add functionality for uploading custom avatar images
  • A modvar should control whether upload functionality is allowed/activated or not.
  • Further settings allow to define maximum size/width/height and whether too large images should be shrinked
  • Deprecate https://github.com/zikula-ev/Avatar
• Update vendors of core to include newest Profile revision
• Update generator, too