Mon Sep 20 00:23:54 CEST 2010

Memory opti

1. Allow for Flash storage of leaf/ex objects.

This requires a modification of free() for leaf objects (to ignore
flash pointers), and the GC such that EX vectors stored in flash are
not taken into account in GC and treated as constants.

2. GC: semisphere -> mark/sweep

3. Hash consing?

The last two introduce more tag bits.  The former should be