Initial Clone/RemoveSprite and Drag/Drop stuff (SWF only for now).
Although it's not explicitly stated in the SWF specification, only GROUPS can be cloned, not text or shapes. Also, RemoveSprite isn't having any effect in either Gnash or the official Adobe player, although it appears to be implemented correctly; further investigation is needed to figure out why. In other news, SWF files now use different types of PlaceObject/RemoveObject tag depending on the version specified. As a result, Lightspark will now (partially) render files exported with the AVM2 flag set. Additionally, the latest known SWF version has been bumped to 25.