libsocket.tex: send[to] returns nbytes.
libstring.tex: added count().
ref2.tex: new keywords; moved keyword printing program to keywords.py.
diff --git a/Doc/lib/libstring.tex b/Doc/lib/libstring.tex
index 2bcbdfc..bf7ad09 100644
--- a/Doc/lib/libstring.tex
+++ b/Doc/lib/libstring.tex
@@ -130,6 +130,12 @@
not found.
\end{funcdesc}
+\begin{funcdesc}{count}{s\, sub\, i}
+Return the number of (non-overlapping) occurrences of substring
+\var{sub} in string \var{s} with index at least \var{i}.
+If \var{i} is omitted, it defaults to \code{0}.
+\end{funcdesc}
+
\begin{funcdesc}{lower}{s}
Convert letters to lower case.
\end{funcdesc}