libtorc-baseui: Better menu navigation for detached groups

- don't pass the selection Up/Down for detached vertical groups
- don't pass the selection Left/Rght for detached horizontal groups
- grids aren't changed but a detached grid is probably a bad idea
libtorc-core: Add TorcSetting class

- which needs some explainig...
libtorc-core: Add some top level Audio and Video settings groups
libtorc-video: Add hardware video decoding settings
libtorc-video: Respect video decoder settings in VDA
libtorc-video: Remove VDA hardcoded disable

- seems to much more stable in more recent OS X releases and can now be
disabled if needed