tracker-extract: Use API to iterate through extract modules
tracker-extract: Use API to iterate through extract modules

This API is always used on the main thread, if some module
(whatever the thread policy it has) can't handle a file, the
task is put back in the main thread so the next module is
called.

hoheinzollern/tracker,outofbits/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker,outofbits/tracker,hoheinzollern/tracker