[jhc] darcs patch: start adding slub allocator (and 4 more)

Mon Apr 5 01:42:27 PDT 2010 John Meacham * start adding slub allocator Mon Apr 5 20:14:20 PDT 2010 John Meacham * add per-object caches Tue Apr 6 15:32:10 PDT 2010 John Meacham * start using bits in pages directly as grey set Tue Apr 6 19:20:03 PDT 2010 John Meacham * keep seperate page lists for partial and fully used pages Tue Apr 6 20:56:53 PDT 2010 John Meacham * performance tweaks and fix ups of jgc code