Add id field to chapter and book tags to allow output file names

 to be meaningful.

doc/src/sgml/protocol.sgml

-<Chapter>
+<Chapter Id="protocol">
 <DocInfo>
 <Author>
 <FirstName>Phil</FirstName>

doc/src/sgml/psql.sgml

-<Chapter>
+<Chapter Id="psql">
 <Title><Command>psql</Command></Title>
 
 <Para>

doc/src/sgml/query-ug.sgml

-<Chapter>
+<Chapter Id="query-ug">
 <TITLE>The Query Language</TITLE>
 
 <Para>

doc/src/sgml/query.sgml

-<Chapter ID="QUERY">
+<Chapter ID="query">
 <TITLE>The Query Language</TITLE>
 
 <Para>

doc/src/sgml/recovery.sgml

-<Chapter>
+<Chapter Id="recovery">
 <Title>Database Recovery</Title>
 
 <Para>

doc/src/sgml/regress.sgml

-<Chapter>
+<Chapter Id="regress">
 <Title>Regression Test</Title>
 
 <Abstract>

doc/src/sgml/rules.sgml

-<Chapter>
+<Chapter Id="rules">
 <Title>The <ProductName>Postgres</ProductName> Rule System</Title>
 
 <Para>

doc/src/sgml/spi.sgml

-<Chapter>
+<Chapter Id="spi">
 <DocInfo>
 <AuthorGroup>
 <Author>

doc/src/sgml/start-ag.sgml

@@ -4,7 +4,7 @@
 -	- thomas 1998-02-24
 -->
 
-<Chapter>
+<Chapter Id="start-ag">
 <Title>Runtime Environment</Title>
 
 <Para>
@@ -153,7 +153,7 @@ There is one evident drawback of using locale - it's speed ! So, use locale only
 
 </Chapter>
 
-<Chapter>
+<Chapter Id="postmaster">
 <Title>Starting <Application>postmaster</Application></Title>
 
 <Para>
@@ -186,7 +186,7 @@ There is one evident drawback of using locale - it's speed ! So, use locale only
 </Para>
 </Chapter>
 
-<Chapter>
+<Chapter Id="newuser">
 <Title>Adding and Deleting Users</Title>
 
 <Para>
@@ -200,7 +200,7 @@ to the underlying
 </Para>
 </Chapter>
 
-<Chapter>
+<Chapter Id="disk">
 <Title>Disk Management</Title>
 
 <Para>
@@ -266,7 +266,7 @@ To test the new location, create a database <Database>test</Database> by typing
 </Sect1>
 </Chapter>
 
-<Chapter>
+<Chapter Id="trouble">
 <Title>Troubleshooting</Title>
 
 <Para>
@@ -296,7 +296,7 @@ FATAL 1:Feb 17 23:19:55:process userid (2360) != database owner (268)
 </Para>
 </Chapter>
 
-<Chapter>
+<Chapter Id="manage-ag">
 <Title>Managing a Database</Title>
 
 <Para>

doc/src/sgml/storage.sgml

-<Chapter>
+<Chapter Id="storage">
 <Title>Disk Storage</Title>
 
 <Para>

doc/src/sgml/trigger.sgml

-<Chapter>
+<Chapter Id="triggers">
 <Title>Triggers</Title>
 
 <Para>

doc/src/sgml/tutorial.sgml

@@ -12,7 +12,7 @@
 <!entity advanced SYSTEM "advanced.sgml">
 <!entity biblio   SYSTEM "biblio.sgml">
 ]>
-<Book>
+<Book Id="tutorial">
 
 <!-- Title information -->
 

doc/src/sgml/typeconv.sgml

-<chapter>
+<chapter Id="typeconv">
 <title>Type Conversion</title>
 
 <para>

doc/src/sgml/user.sgml

@@ -23,7 +23,7 @@
 <!entity biblio   SYSTEM "biblio.sgml">
 ]>
 <!-- entity manpages SYSTEM "man/manpages.sgml" subdoc -->
-<Book>
+<Book Id="user">
 
 <!-- Title information -->
 

doc/src/sgml/xaggr.sgml

-<Chapter>
+<Chapter Id="xaggr">
 <Title>Extending <Acronym>SQL</Acronym>: Aggregates</Title>
 
 <Para>

doc/src/sgml/xfunc.sgml

-<Chapter>
+<Chapter Id="xfunc">
 <Title>Extending <Acronym>SQL</Acronym>: Functions</Title>
 
 <Para>

doc/src/sgml/xindex.sgml

-<Chapter>
+<Chapter Id="xindex">
 <Title>Interfacing Extensions To Indices</Title>
 
 <Para>

doc/src/sgml/xoper.sgml

-<Chapter>
+<Chapter Id="xoper">
 <Title>Extending <Acronym>SQL</Acronym>: Operators</Title>
 
 <Para>

doc/src/sgml/xtypes.sgml

-<Chapter>
+<Chapter Id="xtypes">
 <Title>Extending <Acronym>SQL</Acronym>: Types</Title>
 <Para>
      As previously mentioned, there are two kinds  of  types