Move a step closer to autoplugging. The element selection in the pipeline works.

Move a step closer to autoplugging. The element selection in the pipeline works.

Original commit message from CVS:
Move a step closer to autoplugging. The element selection in the
pipeline works.
Slight modification to the typefind function handling.
removed the stupid mime types in the mpeg decoders.
Adjust videosink for the new caps handling.
Modified the queue example to show an error in plan creation; Erik can you
solve this? This is the type of pipelines autoplugging uses.