Add ChangeLog and documentation for signature dict enhancements

ChangeLog

@@ -1,3 +1,29 @@
+2019-10-22  Jay Berkenbilt  <ejb@ql.org>
+
+	* Incorporate changes from Masamichi Hosoda <trueroad@trueroad.jp>
+	to properly handle signature in the following ways:
+	  - Always represent /Contents in a signature dictionary as a hex
+	    string
+	  - Do not compress signature dictionaries when generating object
+	    streams
+	  - Do not encrypt/decrypt the /Contents field of the signature
+	    dictionary when creating or reading encrypted files
+
+	* Incorporate changes from Masamichi Hosoda <trueroad@trueroad.jp>
+	to add additional methods for making it possible to gain deeper
+	insight into cross reference tables and object renumbering. These
+	new API calls make it possible for applications to go into PDF
+	files created by qpdf and make changes to them that go beyond
+	working with the PDF at the object level. The specific use case
+	for these changes was to write an external tool to perform digital
+	signature, but there could be other uses as well. New methods
+	include the following, all of which are described in their
+	respective headers:
+	  - QPDF::getXRefTable()
+	  - QPDFObjectHandle::getParsedOffset()
+	  - QPDFWriter::getRenumberedObjGen(QPDFObjGen)
+	  - QPDFWriter::getWrittenXRefTable()
+
 2019-10-12  Jay Berkenbilt  <ejb@ql.org>
 
 	* 9.0.2: release

manual/qpdf-manual.xml

@@ -4363,6 +4363,45 @@ print "\n";
    For a detailed list of changes, please see the file
    <filename>ChangeLog</filename> in the source distribution.
   </para>
+  <variablelist>
+   <varlistentry>
+    <term>9.1.0: XXX</term>
+    <listitem>
+     <itemizedlist>
+      <listitem>
+       <para>
+         Library Enhancements
+       </para>
+       <itemizedlist>
+         <listitem>
+           <para>
+             Incorporate contribution from Masamichi Hosoda to
+             properly handle signature dictionaries by not including
+             them in object streams, formatting the
+             <literal>/Contents</literal> key has a hexadecimal
+             string, and excluding the <literal>/Contents</literal>
+             key from encryption and decryption.
+           </para>
+         </listitem>
+         <listitem>
+           <para>
+             Incorporate contribution from Masamichi Hosoda to provide
+             new API calls for getting file-level information about
+             input and output files, enabling certain operations on
+             the files at the file level rather than the object level.
+             New methods include
+             <function>QPDF::getXRefTable()</function>,
+             <function>QPDFObjectHandle::getParsedOffset()</function>,
+             <function>QPDFWriter::getRenumberedObjGen(QPDFObjGen)</function>,
+             and <function>QPDFWriter::getWrittenXRefTable()</function>.
+           </para>
+         </listitem>
+       </itemizedlist>
+      </listitem>
+     </itemizedlist>
+    </listitem>
+   </varlistentry>
+  </variablelist>
   <variablelist>
    <varlistentry>
     <term>9.0.2: October 12, 2019</term>