ad 5.x-1.3-1

1.3.1 is a brown paper bag release fixing a typo that prevented ads from being displayed when the file cache was enabled.

Changes in version 1.3:

• Feature: invisible image mechanism for counting ad views without using JavaScript.
• Feature: adserve tracks which ads have been displayed, so can be called multiple times without displaying duplicate ads.
• New file: most logic from adserve.php was moved into adserve.inc.
• New file: imageserve.inc, provides a mechanism for counting ad views using invisible images.