Use dcp::filesystem to wrap filesystem calls and fix_long_path anything that is passed to read_file() from libcxml. This should fix #2623 and other similar problems.
Extract Film::Property to its own header to (maybe) increase compilation speed.
Remove some more unnecessary use of shared_ptr.
Rearrange subtitle font management. With this change each subtitle coming out of the player has a reference to a dcpomatic::Font that belongs to the TextContent. This hopefully solves a few problems which all basically stemmed from the fact that previously the decoders/player were deciding what the font ID in the output DCP would be - they can't do that properly.
C++11 tidying.
Make DCP text track language properly optional and ignore bad values on imported DCPs (#1950).
Put subtitle language back into content from the film (#1930). This also adds the main/additional language flag. Of all the considerations about how to specify subtitle language, the most important seems to be that the language specification happens for the content where the language is; i.e. in the content text tab.
More enum class additions.
BOOST_FOREACH.
std::shared_ptr
Pass fonts from content around as FontData. i.e. as a block of memory rather than a file. Also, get the fonts from the decoder rather than the content. Together, these changes allow us to use fonts from SMPTE DCPs added as content. Before, fonts would be messed up in those cases (#1885).
Fix lots of macOS warnings by using a different boost/bind include.
Subtitle language test updates.
Subtitle language handling tweaks; write multiple subtitle languages to SMPTE extended metadata.
Store subtitle language(s) in Film, and allow setup of those languages from the Interop/SMPTE metadata dialogues.
Try to clean up the mess of exporting subtitles when there is one file vs many files (multiple reels or fonts).
Add option to export Interop subs with or without the font file / reference.
Make sure subtitle exports have .xml extension.
Write empty files when exporting subtitles and finding none.
Primitive subtitle export feature.