Blender Git Loki

More assorted Keying Sets changes for Cessen (mainly api stuff):

* Added operator (Ctrl Shift Alt I) to show menu for changing the active Keying Set in the 3D view (todo item from last commit)

* KeyingSetInfo (i.e. the Builtin Keying Set classes) can now be accessed from Keying Set instances with ks.type_info
* Added ks.remove_all_paths() function to remove all the paths for a Keying Set.

---

These two changes mean that builtin Keying Sets could be refreshed in response to context changes by doing:
<code>
ks = bpy.context.scene.active_keying_set
if ks.absolute==False and ks.type_info:
ksi = ks.type_info

# remove existing paths to fill with new
ks.remove_all_paths()

# check if Keying Set can be used in current context
if ksi.poll(bpy.context):
# call iterator() which calls generate() and re-populates paths list
ksi.iterator(bpy.context, ks)
</code>

And then, once this has been done, the paths that the Keying Set will operate on can be accessed as
<code>
paths = bpy.context.scene.active_keying_set.paths
</code>