added theme support by encapsulating everything in html <diff> containers (presets 'right scroll', 'right', 'left scroll', 'left' -> the 'scroll' presets enables the user to see what the changes do without up/down scrolling; renamed preview.php to download_preview.php and corrected all needed links -> there was a discrepance in preview.php for the naming convention; modified 'config.php' so that 'CAM_STRING' reflects the cam only and the 'APP_NAME' got an extra position