To use KeyingSets, simply Outliner-select items in the Datablocks view and press K to add to the active KeyingSet. Then keyframes can be inserted by choosing the 'Active Keying Set' option when inserting keyframes.
Important notes on the current implementation:
* Only properties directly inside some ID-block that is close to the root (i.e. main -> objects -> "someobj" -> location, or main -> materials -> "somemat" -> colour) can be accessed for now, as I haven't got the code for building the inner-parts of the paths working yet. Help on getting this working is welcome (hint to Brecht).
* Properties that can be safely included include simple properties "object -> Dupli Verts", entire arrays "object -> Location" or individual array elements "object -> Location -> y"
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Also added typo fix for KeyingSet freeing. It was freeing the KeyingSet instead of it's paths.
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