More correct fix for #19823

The last fix assumed that the removed item was one of the changed items, but
that doesn't have to be true.

The new approach uses 2 sql statements to check if items have been added, but
both should be very quick.
Better logging in httpclient
bz19864: display queued downloads on the downloads tab
bz19852: fix playback on windows
Avoid calling startup.initialize() twice.

This prevents us from duplicating the logging output.