Download location:
<http://www.httrack.com/index.php?p=2>

Summary of all changes since 3.16-2:
+ New: HTTPS support (SSL)
+ New: ipv6 support
+ New: 'longdesc' added
+ New: new file 'new.txt' generated for transfer status 
reports
+ New: ISO9660 compatibility option
+ New: empty mirror/update detection improved
+ New: Update hack now recognizes "imported" files
+ New: Option to disable ipv4/ipv6
+ New: Filters now recognize patterns like -https://*
+ Fixed: The engine should be now fully reentrant
+ Fixed: Fixes for alpha and other 64-bit systems
+ Fixed: Files downloaded twice if not found in cache
+ Fixed: ftp problems with 2xx responses
+ Fixed: ftp problems with multiple lines responses
+ Fixed: ftp %20 not escaped anymore
+ Fixed: ftp RETR with quotes problems
+ Fixed: now tolerent to empty header responses
+ Fixed: hts-log closed
+ Fixed: Compressed pages during updates
+ Fixed: Crash when receiving empty compressed pages
+ Fixed: Random crashes in 'spider' mode
+ Fixed: bcopy/bzero not used anymore..
+ Fixed: various code cleanups
+ Fixed: Better UTF8 detection
+ Fixed: External links now work with https and ftp
+ Fixed: Top index.html corrupted or missing
+ Fixed: URL list crashes
+ Fixed: Random crashes with large sites due to bogus 
naming handler
+ Fixed: Freezes on some robots.txt files
+ Fixed: Compressed files not stored
+ Fixed: SVG fixes
+ Fixed: Raw HTML responses
+ Fixed: 406 error workaround
+ Fixed: Crashes due to binary files with bogus HTML type 
(not parsed anymore)
+ Fixed: External https and ftp links broken, relative 
https links broken
+ Fixed: Automatic resizing of filter stack
+ Fixed: Various ampersand (&) elements added
+ Fixed: https with proxy temporary workaround (direct 
connection)
+ Fixed: "base href" with absolute uris
+ Fixed: stack frame too large on some systems
+ Fixed: random bad requests due to bogus authentication
+ Shell: Several fixes, including registration type problems
+ Shell: "template files not found" fixed