Reformat documentation of libpq escaping functions.

Modify the "Escaping Strings for Inclusion in SQL Commands" section
to use a <variablelist> as the preceding and following sections do,
and merge the "Escaping Binary Strings for Inclusion in SQL Commands"
section into it.

This changes only the formatting of these sections, not the content.
It is intended to lay the groundwork for a follow-on patch to add
some new escaping functions, but it makes sense to commit this first,
for clarity.

doc/src/sgml/libpq.sgml

-<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.292 2009/12/02 14:07:25 momjian Exp $ -->
+<!-- $PostgreSQL: pgsql/doc/src/sgml/libpq.sgml,v 1.293 2010/01/20 00:42:28 rhaas Exp $ -->
 
 <chapter id="libpq">
  <title><application>libpq</application> - C Library</title>
@@ -2925,31 +2925,37 @@ typedef struct {
   <sect2 id="libpq-exec-escape-string">
    <title>Escaping Strings for Inclusion in SQL Commands</title>
 
-   <indexterm zone="libpq-exec-escape-string">
-    <primary>PQescapeStringConn</primary>
-   </indexterm>
-   <indexterm zone="libpq-exec-escape-string">
-    <primary>PQescapeString</primary>
-   </indexterm>
    <indexterm zone="libpq-exec-escape-string">
     <primary>escaping strings</primary>
     <secondary>in libpq</secondary>
    </indexterm>
 
+   <variablelist>
+    <varlistentry>
+     <term>
+      <function>PQescapeStringConn</function>
+      <indexterm>
+       <primary>PQescapeStringConn</primary>
+      </indexterm>
+     </term>
+
+     <listitem>
      <para>
-    <function>PQescapeStringConn</function> escapes a string for use within an SQL
-    command.  This is useful when inserting data values as literal constants
-    in SQL commands.  Certain characters (such as quotes and backslashes) must
-    be escaped to prevent them from being interpreted specially by the SQL parser.
+      <function>PQescapeStringConn</function> escapes a string for
+      use within an SQL command.  This is useful when inserting data
+      values as literal constants in SQL commands.  Certain characters
+      (such as quotes and backslashes) must be escaped to prevent them
+      from being interpreted specially by the SQL parser.
       <function>PQescapeStringConn</> performs this operation.
      </para>
 
      <tip>
       <para>
-     It is especially important to do proper escaping when handling strings that
-     were received from an untrustworthy source.  Otherwise there is a security
-     risk: you are vulnerable to <quote>SQL injection</> attacks wherein unwanted
-     SQL commands are fed to your database.
+       It is especially important to do proper escaping when handling
+       strings that were received from an untrustworthy source.
+       Otherwise there is a security risk: you are vulnerable to
+       <quote>SQL injection</> attacks wherein unwanted SQL commands are
+       fed to your database.
       </para>
      </tip>
 
@@ -3000,7 +3006,18 @@ typedef struct {
       <function>PQescapeStringConn</> returns the number of bytes written
       to <parameter>to</>, not including the terminating zero byte.
      </para>
+     </listitem>
+    </varlistentry>
 
+    <varlistentry>
+     <term>
+      <function>PQescapeString</function>
+      <indexterm>
+       <primary>PQescapeString</primary>
+      </indexterm>
+     </term>
+
+     <listitem>
      <para>
       <synopsis>
        size_t PQescapeString (char *to, const char *from, size_t length);
@@ -3025,18 +3042,9 @@ typedef struct {
       hazard and should be avoided in favor of
       <function>PQescapeStringConn</>.
      </para>
-  </sect2>
-
-
-  <sect2 id="libpq-exec-escape-bytea">
-   <title>Escaping Binary Strings for Inclusion in SQL Commands</title>
-
-   <indexterm zone="libpq-exec-escape-bytea">
-    <primary>bytea</primary>
-    <secondary sortas="libpq">in libpq</secondary>
-   </indexterm>
+     </listitem>
+    </varlistentry>
 
-   <variablelist>
     <varlistentry>
      <term>
       <function>PQescapeByteaConn</function>