#25 Exif Accessor Doesn't Show Write Errors

[Daniel Rupe]

If an Accessor is obtained like this:

PmtAccessorPtr acc = PmtAccessor::getAccessor(testFile);

and a subsequent writeMetadata() call is made on it, no error of any kind is detected.

Since the 'mode' parameter in getAccessor defaults to PMT_READONLY, it is not possible to write
to the opened file. However, no errors of any kind are returned from a writeMetadata() call to
a read-only file. Even if throwErrors() is set to true, no errors are thrown.

writeMetadata() should throw an error (when throwErrors() is set to true) if it's called on a
read-only file.