Thu Nov 5 17:34:05 CET 2009

GC restarts and reading

Reading is stateful: it can't trigger a restart.  This is best solved
by calling the collector before read.

Growing the heap:  restart loops need to be detected.

fixed with gc->margin check after collection.  Currently set at 100
cells.  (Heuristic: 11 is not enough for SC and triggers a restart