Search field for PVR TV/Radio channels and Recordings.

[Selaron]

In the views Music, TV Shows and Movies there is a magnifier icon after tipping on which you can input a search term filtering the lists.

I'd like to implement a search field like this for PVR secions: TV Channels Radio Channels Recordings.

As Kodi JSON API does not seeme to support filtering parameters for PVR data, the filtering would need to be implemented within the app after the full list of items has been received from the server.

Some PVRs have a large number of Channels (especially when used with SAT) and recordings. Even though recordings can now (eventually) be sorted (#385 if PR gets merged ) a search field would help to find desired recordings (and channels) even faster.

I'm ready to prepare a PullRequest.

[Selaron]

The search input functionality is implemented in AbstractCursorListFragment but it would not be viable to extend from AbstractCursorListFragment with PVRRecordingsListFragment as no database is queried by PVRRecordingsListFragment.

Should search functionality (menu item + SearchView) instead be pulled up into AbstractListFragment so that PVRRecordingsListFragment can extend AbstractListFragment ?