Add recent videos option

As a result of a conversation with @jeroenpardon, I wrote this to see if it was possible and it seems to work well. It provides the option to return a list of recent videos - that is to say recent movies and recent episodes interleaved into one list.

Whilst this list will be slightly slower to display than others, as it has to process the data from both movies and episodes and then interleave them, the script doesn't have to fetch any extra data, nor does this affect any other listing methods. Therefore the speed of initial data caching and listing of other types should not be affected.

The new list doesn't return any content type, as I am not aware of any content type for mixed movies and episodes. As far as I am aware, there is no known issue returning both content types in a single list - I did ask in the python development forum, but got no response.