1.0.37.30: OAOOize type of NAME slots between THREAD, MUTEX &c.

1.0.37.30: OAOOize type of NAME slots between THREAD, MUTEX &c.

  * Introduce new type THREAD-NAME; it expands to SIMPLE-STRING for
    now; that's what some of the thread-related data structures
    (MUTEX, WAITQUEUE) used in past whereas others allowed anything
    (THREAD).

  * Use that type consistently for THREADs, MUTEXes, WAITQUEUES,
    SPINLOCKs and SEMAPHOREs.