Make hybrid pdfs when converting ppt materials to pdf. Fixes ietf-tools#2769. Commit ready for merge.

 - Legacy-Id: 16818

Author: rjsparks

ietf/settings.py

@@ -875,7 +875,7 @@ def skip_unreadable_post(record):
 SECR_INTERIM_LISTING_DIR = '/a/www/www6/meeting/interim'
 SECR_MAX_UPLOAD_SIZE = 40960000
 SECR_PROCEEDINGS_DIR = '/a/www/www6s/proceedings/'
-SECR_PPT2PDF_COMMAND = ['/usr/bin/soffice','--headless','--convert-to','pdf','--outdir']
+SECR_PPT2PDF_COMMAND = ['/usr/bin/soffice','--headless','--convert-to','pdf:writer_globaldocument_pdf_Export','--outdir']
 STATS_REGISTRATION_ATTENDEES_JSON_URL = 'https://ietf.org/registration/attendees/{number}'
 NEW_PROCEEDINGS_START = 95
 USE_ETAGS=True