Split fpdfdoc/include/fpdf_doc.h into individual classes.

This CL splits the header file apart. The cpp files are not touched as part
of this CL, they will be done as a followup. This de-duplicates the fpdf_doc.h

BUG=pdfium:249

Review-Url: https://codereview.chromium.org/2183313004
diff --git a/fpdfsdk/fpdfeditpage.cpp b/fpdfsdk/fpdfeditpage.cpp
index 439f73a..0d0dac4 100644
--- a/fpdfsdk/fpdfeditpage.cpp
+++ b/fpdfsdk/fpdfeditpage.cpp
@@ -19,6 +19,8 @@
 #include "core/fpdfapi/fpdf_parser/include/cpdf_document.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_number.h"
 #include "core/fpdfapi/fpdf_parser/include/cpdf_string.h"
+#include "core/fpdfdoc/include/cpdf_annot.h"
+#include "core/fpdfdoc/include/cpdf_annotlist.h"
 #include "fpdfsdk/include/fsdk_define.h"
 #include "public/fpdf_formfill.h"
 #include "third_party/base/stl_util.h"