Update the sources to use the renamed CSS types from cainteoir-engine.
cainteoir.cpp: tts::engines::speak no longer takes a document as an argument
cainteoir.cpp: tts::engines::speak now takes the selection object directly
document.hpp: toc is now stored in the cainteoir::document, so use that instead of a custom version
cainteoir.cpp: use cainteoir::document directly instead of a custom document class
cainteoir.cpp: application_settings is not used in create_buffer_from_document, so remove it
create_buffer_from_document: just pass the cainteoir::document object
create_buffer_from_document: move from cainteoir.cpp to document.hpp
regression: fix a crash if there is no document loaded
Create a libcainteoir-gtk library containing the GtkTextBuffer helpers.
autotools: require nullptr support
autotools: require std::begin and std::end support
Fix the use of the language and region helpers after the API change.
Update the po files.
Add the transifex translation service configuration file.
The open_audio_device method signature has changed, so update the usage of it.
don't use 'g_type_init' if built with glib 2.36 or later
GNOME3: the Music app does not place any buttons on the top bar
GNOME3: the Music app aligns the top navigation buttons in the center
GNOME3: make the bottom bar match the Music app styling