[jboss-as7-dev] Removing thread subsystem

Hi, Threads subsystem has not been directly used since 7.1.0.CR1. see https://issues.jboss.org/browse/AS7-390 for more details. The only usage we have is that EJB3 & JCA subsystems use some common code from threads subsystem (parser & few RD) but beyond that subsystem is unused aka we could remove ThreadExtension and everything would still work. And ever since there was no need for thread subsystem enabled/deployed in configuration but we still had it in all our default shipped configs. I would like to remove it from our default shipped configurations as it does not effect any functionality. Also I have introduced option to "deprecate" extension, so it now logs warning when such extension is registered (aka is found in configuration) As goes for compatibility issues in mixed-domain this change does not effect 7.1.0+/EAP6 as they can properly operate without this subsystem. It looks like that we removed usage of Threads subsystem in 7.1.0.CR1 but forgot to remove it from shipped configurations. my current effort at this can be found at https://github.com/ctomc/jboss-as/compare/threads (there is lots of removed redundant & old style tests) -- tomaz