Fixed bug in QWaveDecoder.

When looking for a specific chunk, it was entering an infinite loop if not
finding it in the next two chunks available. It now correctly tries to
find the chunk until it reaches the end of the IO device.

Change-Id: I29252318566fe3a47f267410c91dacaf302d9618
Reviewed-by: Andy Nichols <andy.nichols@digia.com>
Implement resource policy plugin using libresourceqt.

This contains a new resource policy plugin, replacing the built-in
code that was deleted when the plugin interface was removed in
138242fb2dc19438a0ead34b36af848800e27190 (which unfortunately did not provide a
plugin).

Change-Id: Iae7ed6edc330c69ca0c72d50bde6c7e12b8cca4e
Reviewed-by: Andy Nichols <andy.nichols@digia.com>