New: Option to show the paths of Bones over time.

In PoseMode, press Wkey or use the Pose pulldown menu. It calculates the
positions of all selected Bone end points, over the time as indicated with
the Scene start/end frame. This then is drawn as a path, with little black
dots on every frame, and a white dot on every 10 frames.

Paths are not saved in files, and not calculated automatic yet on changes.

To make this relative fast, but also reliable, I had to add a new method
in the Dependency graph system, to find exactly (and only) these parents
of an Object that influence its position. This is needed because the path
should show the actual global coordinates of the entire animation system.

source/blender/include/BIF_poseobject.h

@@ -60,6 +60,9 @@ void paste_posebuf (int flip);
 
 void pose_adds_vgroups(struct Object *meshobj);
 
+void pose_calculate_path(struct Object *ob);
+void pose_clear_paths(struct Object *ob);
+
 void pose_flip_names(void);
 void pose_activate_flipped_bone(void);