Several transformations on DataBuf + migration to size_t

- Provide begin/end iterators to DataBuf and simplify code
- Adapt test output after last changes
- Replacing long by size_t in value.hpp
- Use size_t in some Photoshop functions
- Remove some static_casts

tests/bugfixes/github/test_CVE_2018_12265.py

@@ -18,7 +18,6 @@ class AdditionOverflowInLoaderExifJpeg(metaclass=system_tests.CaseMeta):
 Warning: Directory Image, entry 0x0201: Strip 0 is outside of the data area; ignored.
 Warning: Directory Image, entry 0x0201: Strip 7 is outside of the data area; ignored.
 Error: Offset of directory Thumbnail, entry 0x0201 is out of bounds: Offset = 0x00000000; truncating the entry
-$uncaught_exception $addition_overflow_message
 """
     ]
-    retval = [1]
+    retval = [0]

tests/bugfixes/github/test_issue_428.py

@@ -17,25 +17,22 @@ class PngReadRawProfile(metaclass=system_tests.CaseMeta):
         system_tests.path("$data_path/issue_428_poc4.png"),
         system_tests.path("$data_path/issue_428_poc5.png"),
         system_tests.path("$data_path/issue_428_poc8.png"),
+        system_tests.path("$data_path/issue_428_poc7.png"),
 
         system_tests.path("$data_path/issue_428_poc2.png"),
         system_tests.path("$data_path/issue_428_poc6.png"),
-        system_tests.path("$data_path/issue_428_poc7.png"),
     ]
 
     commands = ["$exiv2 " + fname for fname in filenames]
     stdout = [""] * len(filenames)
-    stderr = [ stderr_exception(fname) for fname in filenames[0:5] ]
+    stderr = [ stderr_exception(fname) for fname in filenames[0:6] ]
 
-    stderr.append("""$exiv2_exception_message """ + filenames[5] + """:
+    stderr.append("""$exiv2_exception_message """ + filenames[6] + """:
 $kerInputDataReadFailed
 """)
 
     stderr.append("""Error: XMP Toolkit error 201: Error in XMLValidator
 Warning: Failed to decode XMP metadata.
-""" + stderr_exception(filenames[6]))
-
-    stderr.append("""Warning: Failed to decode Exif metadata.
 """ + stderr_exception(filenames[7]))
 
     retval = [1] * len(filenames)