Reduce assumptions in examples

-dynamic scene, don't set duration on running animation (doesn't work)
-dynamic scene, just use set colors instead of system palette (in case
platform doesn't support it right, like N900)
-dynamic scene, calculator and shadereffects, don't rely on root item being
automatically in scope (possibly confusing)

Change-Id: I1eec018d5387424dc6b07bf51c1b2184b3048553
Reviewed-by: Yann Bodson <yann.bodson@nokia.com>