cosmetics.
exposed renderer::Frame::transform_to_output_color_space() in the Python API.
Merge branch 'master' of github.com:jupiter-jazz/appleseed
tweaked error messages.
changed foundation::Path::get_executable_path() and foundation::Path::get_executable_directory() to free functions.
added foundation::split_paths().
removed many inclusions of renderer/global/global.h.
removed more inclusions of renderer/global/global.h.
texture instances' alpha mode detection is now performed in an on_frame_begin() handler rather than during input binding.
tweaked formatting.
tweaked comment.
added infrastructure to support aborting rendering during scene preparation, and improved aborting mechanism.

at this point, the following operations can be aborted:
  - preparation of scene entities (calling of on_frame_begin() handlers)
  - construction of latitude-longitude importance maps

the following operations cannot yet be aborted:
  - geometry collection
  - building of acceleration structures
  - construction of intersection filters
in appleseed.studio, only compute the final average luminance if the print_final_average_luminance setting is set to true (false by default).
updated appleseed.studio's settings file.
improved handling of assets when writing project files to disk.
prune redundant transforms in transform sequences.