Remove all \bcode / \ecode cruft; this is no longer needed.  See previous
checkin of myformat.sty.

Change "\renewcommand{\indexsubitem}{(...)}" to "\setindexsubitem{(...)}"
everywhere.

Some other minor nits that I happened to come across.
diff --git a/Doc/libstring.tex b/Doc/libstring.tex
index 1911801..7242c53 100644
--- a/Doc/libstring.tex
+++ b/Doc/libstring.tex
@@ -10,7 +10,7 @@
 
 The constants defined in this module are are:
 
-\renewcommand{\indexsubitem}{(data in module string)}
+\setindexsubitem{(data in module string)}
 \begin{datadesc}{digits}
   The string \code{'0123456789'}.
 \end{datadesc}
@@ -54,7 +54,7 @@
 
 The functions defined in this module are:
 
-\renewcommand{\indexsubitem}{(in module string)}
+\setindexsubitem{(in module string)}
 
 \begin{funcdesc}{atof}{s}
 Convert a string to a floating point number.  The string must have