igorV is absolutely correct.
I recently installed Mint 13 and Mint 14 Cinnamon editions, neither of which came with a menu option for a screensaver slideshow. Installed but absolutely could not get xscreensaver to run the GLSlideshow using the family images in my /home/(user)/Pictures folder; all I could get was a single multi-colored screen test pattern. The other optional screensaver modes (swimming fish, hypertorus,etc.) seemed to run just fine. After two days of installing, uninstalling, searching the Internet and trying every possible option I could think of, I came across igorV's posting to install the libwww-perl package using the package manager, or you can use the terminal to enter "apt-get install libwww-perl". Instant success.