Split off CPDF_Document into its own .cpp/.h files.

core/src/fpdfapi/fpdf_edit/fpdf_edit_create.cpp

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #include "core/src/fpdfapi/fpdf_edit/editint.h"
 
 #include <vector>
 
+#include "core/include/fpdfapi/cpdf_document.h"
 #include "core/include/fpdfapi/fpdf_parser.h"
 #include "core/include/fpdfapi/fpdf_serial.h"
 #include "core/include/fxcrt/fx_ext.h"
 #include "third_party/base/stl_util.h"
 
 #define PDF_OBJECTSTREAM_MAXLENGTH (256 * 1024)
 #define PDF_XREFSTREAM_MAXSIZE 10000
 
 // TODO(ochang): Make helper for appending "objnum 0 R ".
 
@@ skipping 2035 matching lines @@
   m_bNewCrypto = FALSE;
   if (!m_bStandardSecurity) {
     return;
   }
   if (m_pEncryptDict) {
     m_pEncryptDict->Release();
     m_pEncryptDict = NULL;
   }
   m_bStandardSecurity = FALSE;
 }