InventoryClickEvent

These are the click actions in Packet 102:

 - Shift=0
    - Button 0 = Left Mouse
    - Button 1 = Right Mouse
 - Shift=1
    - Button 0 = Shift + Left Mouse
    - Button 1 = Shift + Right Mouse (identical behavior to shiftleft)
 - Shift=2
    - Button 0-8 = Hotbar key (1-9)
 - ===EVERYTHING BELOW THIS IS NEW IN 1.5 ===
 - Shift=3
    - Button 2 = Middle Mouse (creative copystack)
 - Shift=4
    - Slot = -999
      - Button 0: Left click outside inventory holding nothing
      - Button 1: Right click outside inventory holding nothing
    - Slot != -999
      - Button 0: Q key (drop item)
      - Button 1: Ctrl-Q key (drop stack)
 - Shift=5
    - Button 0, 4: Left, Right drag start
    - Button 1, 5: Left, Right drag slot pick
    - Button 2, 6: Left, Right drag stop
 - Shift=6
    - Any button: Double left click (collect items)