RTF Processing Improvement

[jxb5151]

Newer versions of oletools contain an rtfobj API implementation that was incompatible with the previous implementation from FSF.

The crux of the issue being the new value added here:

for index, orig_len, data in ...

as opposed to what was currently done...

for index, data in ...

There appear to have been several other API changes there.

https://github.com/decalage2/oletools/wiki/rtfobj

It's was quick and trivial fix to get things working using the 'rtf_iter_objects' API method (just add the field ;)). Done here.

It might also be an opportunity also to revisit the way it's being done now (write file to disk then process), in favor of something else (pass the buffer straight to method) if permitted by the current project.