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/lib/libimgfile.tex b/Doc/lib/libimgfile.tex
index 96afc9b..098d59b 100644
--- a/Doc/lib/libimgfile.tex
+++ b/Doc/lib/libimgfile.tex
@@ -9,7 +9,7 @@
 
 The module defines the following variables and functions:
 
-\renewcommand{\indexsubitem}{(in module imgfile)}
+\setindexsubitem{(in module imgfile)}
 \begin{excdesc}{error}
 This exception is raised on all errors, such as unsupported file type, etc.
 \end{excdesc}