Enabled some consistency checks in the gc when compiled without rtldebug (only activated on debug level 1 or higher). Always define _verify_internals to be able to use this. Made it possible to turn on trace messages for the gc only with trace(1,"gc"). This is the embryo of a facility based trace system. Still to do: Raise all the global trace levels to make room for gc only trace at level 1, and fix a framework for trace facilities. Rev: src/array.c:1.137 Rev: src/builtin.cmod:1.113 Rev: src/builtin_functions.c:1.466 Rev: src/gc.c:1.199 Rev: src/gc.h:1.97 Rev: src/mapping.c:1.162 Rev: src/multiset.c:1.68 Rev: src/object.c:1.218 Rev: src/program.c:1.477