Merges all or only selected files of a volafile room into a .zip file and downloads it
* 1.5: REALLY fixed the filename encoding this time
* 1.4: Fixed an issue with filename encoding
* 1.3: Added a second button to download only selected files (checkboxes left of the normal volafile download button)
* 1.2: Made the button prettier
Adds a button to the top of volafile rooms that generates a .zip file containing all or only selected files of the room.