Update mythpython script for new tmdb library.
Fix a typo in the help string.
Add background texture to menu, similar to that used elsewhere but using gradients not images.
Webfrontend: Guide: Line up time string against date string.
Add a recordgroups table and start transitioning to it's use.
On some systems, usleep will fail with a value greater than 1000000-1.  Fix
HLSStreamHandler::run to not exceed 1000000-1.
WebSetup: Display a Question Mark icon instead of [?] for help text links
WebFrontend: Allow the main menu to auto-hide giving more space for content. I will probably end up making this optional as it has the potential on slower browsers/systems to be more of a hinderance than a help.
WebFrontend: Use calc() for browsers that support it, to give more space to the guide data
Fix duration calculation which only happened to work here because I'm in GMT
Webfrontend: Go to two decimal places on percentage widths, result is more accurate at high resolutions.
Services: Allow Dvr::GetTitleList() to be filtered by Recording Group
WebFrontend: Only show titles in Filter/Display Group dropdown which are available in the current recording group
Make ffmpeg call 'streams_changed' again when a DVD PCM stream is changed from PCM_DVD to PCM_S16BE to ensure the correct codec is loaded.

Fixes #11941
Fix compiler warnings spotted by Jonatan Lindblad.
Services: Add GetChannelGroupList method to Guide service
Services: Fix copy/paste error in scripting API version of GetChannelGroupList
Services: Allow filtering by Channel Group in GetProgramGuide
WebFrontend: Support filter by Channel Group in the Guide. Refs #11938
WebFrontend: Keep the date/time drop-downs in the guide in sync when using the left/right arrows to navigate.