simu - lower level

looks like we need a version to work with
what has been mentioned in book.
simu - disallow pairs stored as constants
simu - reserved registers
ops typo
simu - machine-pointer?
simu - primitive explained
simu - complete vector-{ref,set!} primitive
simu - initialize memory
simu - use default ops
simu - testcase fix
simu - read / write to a vector
simu - pointer inc
simu - modify rewrite rules
simu - put things together
simu - stack expansion
simu - rule rewrite explained
simu - need to rewrite to a fixpoint
simu - try applying rules multiple times
simu - rewrite closure done
simu - simplify code, more comments