Before this commit, baking an action would only insert keys that are necessary (i.e. using `INSERTKEY_NEEDED`). When baking to the current Action, if there are no constraints that influence the final animation, there are no additional keys necessary. This makes it appear as if nothing happened. However, when baking to a new Action every additional frame is necessary and thus a key is added for every frame. @mont29 and I agreed that this behaviour is confusing, so this commit changes the behaviour such that baking to the current action and to a new action result in the same baked animation (that is, keyed on every frame).