more fixes, add season ep list

* Add:  info.php: season episode list if displaying season information
* Fix:  info.php: if "genres" variable is not available it throws an
error
* Fix:  info.php: if "actors" variable is not available it throws an
error
* Fix:  index.php: recently added season & episode information was
incorrect. PMS does auto grouping of episodes for a season so only the
season # is available when using this method.
* Fix:  current_activity.php: movie stream activity would not appear
* Fix:  more divide by zero fixes (rcork)