Implemented Backtrace stuff
Bug fix: unpickling of negative integers was off by one (!);
Removed InternalTuple.
More hygienic macros.
Replaced GetUInt by a non-recursive version, that also checks for overflow;
Bug fix in closure allocation (size was off by one);
Removed some "to be done"s.
Primitive frames only appear once in the backtrace.
Removed a "to be checked" comment.
Added atExn.
Implemented atExn;
Exit with an error code when an uncaught exception is raised.
Removed SetArgsAndTaskStack;
Print an error when unimplemented Unregister function is called.
Removed superfluous newline in calls to Error.
Added RAISE_FRAME.
typedef u_char
typedef u_char
Fixed string.sub bug (was signedness problem)
Set trace flag depending on whether environment variable
   ALICE_TRACE_BOOT_LINKER is defined.
Distinguish between sited and unsited primitives
Added TRANSFORM_LABEL
Give GetAbstractRepresentation a sensible type
Primitives support Transforms
Removed obsolete function