optimize for tail recursion in ReadItem
revise what's INLINE in serialize.c
make AddReadRef better as inline by moving rare stuff out
Merge branch '22-more-scalars' into 23
more optimization in serialize.c
Merge branch '22-more-scalars' into 23
yet more optimization in serialize.c
Merge branch '22-more-scalars' into 23
more tweaking
Merge branch '22-more-scalars' into 23