add abbreviation int_of_nat for of_nat::nat=>int;
add int_of_nat versions of all lemmas about int::nat=>int;
move int lemmas into their own section, preparing to remove
#!/usr/bin/env bash
#
# $Id$
#
# psbooklet - rearrange pages of ps file to be printed as booklet (duplex)
#
psbook "$@" | \
pstops '4:0L@.7(21cm,0cm)+1L@.7(21cm,14.85cm),3R@.7(0cm,14.85cm)+2R@.7(0cm,29.7cm)'