Version 1.17 beta 44: Added support for users to close polls (only if they...

Version 1.17 beta 44: Added support for users to close polls (only if they created the poll or if they're the sysop).  I ended up using the ! key for that, since many other keys were already taken.  Also, renamed "Read Me.txt" and "Revision history.txt" so they don't have spaces in the filenames.