Update chosen javascript library

• Fix scrolling though warnings on an ipad

• Handle if the warning category has been unexpectedly deleted by throwing a no permission error instead of erroring.
• On install, update warnings which are using missing warning categories.

• Fix: "Undefined index: warning_category_id" when logging a warning as a reply to a thread

Fix SQL error when importing warning groups from [TH] Warnings into Warning Categories.

• [TH] Warnings must be installed and enabled when installing Warning Improvements.
• Please disable [TH] Warnings after the install finishes due to add-on conflicts in the AdminCP.

Add additional empty() checks to prevent issuing a warning to fail with an internal server error

• Note; you must assign permissions on the warning categories themselves!

AdminCP Warning UI overhaul

• Warning Categories, allow grouping of warnings into groups with permissions per category.
  AdminCP - warning screen
  
  
• Drop & Drag support to order warnings or categories

• Editing a category
  
  

Front-end Warning UI overhaul

• Chosen-based select menu
  Issue warning - select menu
  
  
  
  Issue warning - radioboxes
  
  
• Per-browser option to switch to radio-select boxes

• Fix a missed phrase for "The user {name} could not be found"
• Fix option to disable sending warning conversations so it actually disables them correctly

• Global option to control if warning alerts are sent by default.