core/queue: queue -> priority_queue

core/include/mutex.h

core/include/priority_queue.h

core/include/tcb.h

core/msg.c

core/mutex.c

core/priority_queue.c

sys/include/vtimer.h

sys/posix/include/semaphore.h

sys/posix/pthread/include/pthread_cond.h

sys/posix/pthread/include/pthread_rwlock.h

sys/posix/pthread/pthread.c

sys/posix/pthread/pthread_cond.c

sys/posix/pthread/pthread_rwlock.c

sys/posix/semaphore.c

sys/vtimer/vtimer.c

tests/unittests/tests-core/tests-core-priority-queue.c

tests/unittests/tests-core/tests-core.c

tests/unittests/tests-core/tests-core.h