Modified the "animation reuse" sample code to provide
a simpler example to explain in the recipe.
Also modified variable names to mirror the names used
for the previous "complex animation" example and added
some more comments, to further simplify and support the
recipe.
With some help from pippin, moved variable declarations
into more sensible positions within their functions,
changed a function name, and found a better way
to unref a script once its associated actor has
been destroyed.
Extracted the animation into its own JSON definition,
then create a new script and get the animation each
time a rectangle is clicked.
Removes the need to reparent onto the background and
copy property values to the rectangle after the animation,
and generally much cleaner.
