integrate optional component logging setting into core

This moves the functionality of being able to enable/disable logging for specific components (samba, ffmpeg, json-rpc, cmyth, ...) from the xbmc.debug addon into core. IIRC we didn't have the list setting functionality back when this was added. The advantage of this being in core is that we can use #ifdef's to only show the components that are actually available which is not possible with the addon approach.

Furthermore I've re-arranged the setting to have it's own "Enable component-specific logging..." parent-setting which allows to globally enable/disable logging for all these special components without having to go into the list of components and deselect them all. This idea has been brought up by @joethefox.

Not sure if there's anything we can do about all the already translated strings from the addon language files in case this gets merged.