Set up a tentative output selection mechanism. This is based on an integer
parameter, in practise the record id from pptstream.py:recData, and uses a
command-line option to set the list of record types which should be
printed. Also added command-line option to suppress raw dumpBytes output,
and store the command line option as a global object, as this is the only
practical way to get the values down into the low level routines.