Package thread exposes JVM-faithful java.lang.Thread equivalents for code
running on glojure. Only the static methods whose semantics map cleanly
onto Go's runtime are registered here; instance methods (start, join,
interrupt, ...) would require a synthetic per-goroutine identity layer
and are out of scope for now.
Thread is the placeholder type registered as java.lang.Thread's
reflect.Type. We don't expose Thread instances yet (only static
sleep), so the value just makes (ns-imports *ns*) include the
auto-imported class.