Issue 1286 - Add a content type enum for use with FilterEngine

That's fine with me :) The point here however was to remind anyone who might want modify the enum in the future to update the map as well, as @palant had mentioned in a previous comment. The XXX tag was intended to draw attention to this rather than as a TODO item. So do you want me to remove the tag or the entire comment?

Not that I want to pursue this anymore, but one way of achieving auto-syncing between the enum and map would be to write a macro to define both together ;)