Proxy Link-Forum 2.0.6

• Add icon
• Prevent mixing protected/public when extending entities

• Confirm compatibility with XF2.1
• Ensure creating link forums without add-on enabled does not error

• Rework installer to be more robust.
  • Ensure the src/addons/SV/Utils folder is also uploaded! If it exists, just overwrite.

• Remove redundant SQL queries when proxying a forum.

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

• Remove added column on uninstall
• Remove unused file