Set up variable 'fF' once and use it to conditionalize between
fixed-width font Guidebook.txt and proportional-width font
Guidebook.ps instead of making the width comparison of 'f' and 'F'
each time. There are four instances where it is used; three that
suppress some indentation for the plain text output and one that
manually wraps a couple of long lines for it.
This change shouldn't produce different output from before (last
night) and doesn't need any corresponding change in Guidebook.tex.
1ec6e6f96b