[mythtv-cmyth] Release v1.6.13

This updates the Frodo version of the MythTV PVR addon to v1.6.13.
Even if there's no further Frodo release, I believe it's a good idea to have the newest addon version available in the official repo so that it can be picked up by distro maintaineres.

---
Changelog:
- v1.9.13
     - Added demuxer (optional)
         - Faster channel switching
     - Fixed compatibility with MythTV 0.27 backend
         - Fixed channel icon download
         - Fixed schedule management
     - Fixed recognizing merged channels

- v1.6.12
    - Fixed crash when reconnecting to the backend
    - Fixed setting bookmarks when using MythTV 0.27 backend
    - Fixed usage of priority values (>256)
    - Fixed remaining time zone issues by using UTC based timestamps
    - Schedule management refactoring
        - Fixed recording rule deletion
        - Fixed handling of backend version specific varieties
        - Fixed failed mappings due to gaps in the EPG
        - Various smaller improvements and bug fixes
    - Improved start of Live TV playback

- v1.6.11
    - Added support for MythTV protocol 76 and 77 (MythTV 0.27)
    - Allow the backend to shutdown (by using monitor and playback connections)
    - Reduced startup time (Faster loading of channels)
    - Fixed start time for instant recordings
    - Fixed several smaller memory and multithreading issues
    - Refactored & cleaned up libcmyth (epginfo)