[animation] Add vector variants for ::animate()

Bug 1438 - Implicit Animation API could use animatev variants

The clutter_actor_animate* family of functions use va_lists to
handle the property/value pairs for the final state of the
animation.

Language bindings have problems with variadic arguments functions,
and usually prefer vector-based API which allow a greater level
of control and conversion from native data types.

For each variadic arguments function in the clutter_actor_animate*
family there should be a vector-based version that takes:

  - the number of property/value pairs
  - a constant array of constant strings
  - an array of GValues

Most of the internal implementation can be refactored from the
current one, thus both the var_args and the vector entry points
share a common implementation of the code; then, both versions
of the API are just loops over a list of arguments.

Based on a patch by: Robert Carr <carrr@rpi.edu>

doc/reference/clutter/clutter-sections.txt

@@ -1424,6 +1424,9 @@ clutter_animation_get_interval
 clutter_actor_animate
 clutter_actor_animate_with_timeline
 clutter_actor_animate_with_alpha
+clutter_actor_animatev
+clutter_actor_animate_with_timelinev
+clutter_actor_animate_with_alphav
 
 <SUBSECTION Standard>
 CLUTTER_TYPE_ANIMATION