xF2 Add-on View Sticky Threads 2.1.0

Now available on https://atelieraphelion.com

• Require StandardLib v1.20.0+
• Require php 7.2+
• Require XenForo 2.2+
• XF2.3 support

• Fix add-on icon in XF2.1

• Fix "View sticky threads" permission not working for guests

• Fix viewing sticky threads (vs viewing them on the forum index) not working as expected

• Add an icon
• Rework how the add-on rewrites queries to improve compatibility with other add-ons

• Tweak execution order of class extensions/template modifications/etc to provide predictable ordering
• Add LICENCE and README.MD to redistributable.