* BApplication can now take the job to quit a BLooper at
the application quit. It's rejecting requests from windows too.
* BMediaRoster is using now this service in conjunction with the
MediaRosterUndertaker.
* The BeBook specify that we should have a valid BApplication
before to instantiate the BMediaRoster. While in theory we should
add a debugger call when this situation happens, in pratice this
might lead to more problems. For example libraries might use the
media_kit and create a BApplication object, but they aren't
applications, this is a design problem. So I decided to replace it
with a TRACE call for the moment.
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