Improvement for busy loop in ThreadFeatureInputStream.hasNext()

Hi,

I made a change to org.deegree.feature.stream.ThreadedFeatureInputStream which add a wait(1000) to the while loop in QueueFiller.hasNext()

The reason is that the loop used a lot of of CPU when the features are drawn quicker than they are loaded from the database. This seems to fix this problem. To make sure the code does not deadlock i have set the wait timeout to 1 second.

This is my first github based contribution so i hope i have not made any stupid mistakes :)

Best regards,
Jeroen