Merge branch 'master' into ke

Merge branch 'master' into ke

* master: (71 commits)
  rename file_data_new_simple to file_data_new_group, filedata.c cleanup
  recognize all registered extensions, even if they contain dots
  sidecar_file_priority function is already called with extension as an argument
  call notify functions in in an idle call
  move the grouping code from file_data_new to filelist_read
  separate function fortesting changed files without sidecars
  consistent use of fd->extension
  simplified grouping of sidecars
  fixed filelist_sort_compare_filedata to not return 0 no different files
  always check for sidecars by readdir
  do not use FileData entries with empty path
  updated copyright notice
  added custom tiff loader
  added long-term cache for keywords
  set stereo.fixed default values to hdmi stereo standard
  fixed stereo.fixed preferences
  fixed stereo_temp_disable functionality
  ignore raw image support reported by the pixbuf loader
  fixed using DEBUG_N from multiple threads
  Fix bug 3006812: ensure exif cache is initialized even when all files are unreadable.
  ...