Make DCPExaminer::size() optional and deal with the consequences.
This means we can fix the case of a VF having no known size in a nice way,
in turn fixing problems caused by the fix to #2775.
- [DH] src/lib/copy_dcp_details_to_film.cc
- [DH] src/lib/dcp_content.cc
- [DH] src/lib/dcp_examiner.h
- [DH] src/lib/ffmpeg_content.cc
- [DH] src/lib/ffmpeg_decoder.cc
- [DH] src/lib/ffmpeg_examiner.cc
- [DH] src/lib/ffmpeg_examiner.h
- [DH] src/lib/film.cc
- [DH] src/lib/hints.cc
- [DH] src/lib/image_decoder.cc
- [DH] src/lib/image_examiner.cc
- [DH] src/lib/image_examiner.h
- [DH] src/lib/player.cc
- [DH] src/lib/player_video.cc
- [DH] src/lib/video_content.cc
- [DH] src/lib/video_content.h
- [DH] src/lib/video_examiner.h
- [DH] src/lib/video_mxf_examiner.cc
- [DH] src/lib/video_mxf_examiner.h
- [DH] src/tools/dcpomatic_cli.cc
- [DH] src/tools/dcpomatic_player.cc
- [DH] src/wx/content_menu.cc
- [DH] src/wx/player_information.cc
- [DH] src/wx/video_panel.cc
- [DH] test/dcp_examiner_test.cc
- [DH] test/video_content_scale_test.cc