Improvements to presented order of content over UPNP

[joseph@…]

I've submitted this as pull request on Github, I'm not sure if submitting here is duplicative or proper procedure.

​https://github.com/MythTV/mythtv/pull/19

It can be very hard to use the current sort order for the content items over UPNP especially if you have large numbers of a title and don't know the exact date of the recording.

This patch adds logical folders for date sorted versions of the listings by title and it also applies a subtitle sort to the non-date sorted title list to help where you know the particular episode that you want.

I have tested these changes on Ubuntu Precise but have not built from the Git source. I think that this is a very low risk change.

I understand if the design choices you make do not want to offer all these choices but as a heavy UPNP user I would strongly request that you do make a user obvious sort apply to the title grouped content (and I suggest by date). I also understand if you need to change the names, especially if internationalisation is required but I wanted to offer this upstream anyway.