downloadbzbugs: Extract inline attachments as files
downloadbzbugs: Extract inline attachments as files

Decode the base64-encoded attachments data and store each attachment in
a file to ease conversion to the Phill format. Once extracted, strip the
now externally stored attachments data from the XML files.

Differential Revision: https://phabricator.freedesktop.org/D649

thiblahute/bztophill