lots of internal cleaning and tuning;
removed {parse,print}_{pre,post}_proc;
new lexer: now human readable due to scanner combinators;
new parser installed, but still inactive (due to grammar ambiguities);
added Syntax.test_read;
typ_of_term: sorts now made distinct and sorted;
mixfix: added forced line breaks (//);
PROP now printed before subterm of type prop with non-const head;
#! /bin/sh
# teeinput -- start a program and log all inputs to a file
# environment variable $LISTEN specifies the file name
tee -a -i $LISTEN | $*