[easytag] (27 commits) Non-fast-forward update to branch wip/core-refactoring

[David King <davidk src gnome org>]

The branch 'wip/core-refactoring' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  7df8e09... Update version to 2.5.1 on master
  98f4438... Mark up a string for translation

Commits added to the branch:

  4df33c1... Document that Yelp is required at runtime (*)
  3dbfd06... Open the online help if Yelp is not installed (*)
  fe5e205... Fix a bogus check when reading Ogg tags (*)
  2437156... Mention use of C89 comment style in HACKING (*)
  4503eff... Fix possible overflow of reads in the file list (*)
  04c7e16... Added Occitan translation (*)
  c985c83... Updated Occitan translation (*)
  3cc462c... Fix FLAC build when Ogg support is disabled (*)
  9f40d46... Updated Spanish translation (*)
  c3aeb58... Updated Spanish translation (*)
  55ef174... Updated Spanish translation (*)
  bf444c9... Updated Spanish translation (*)
  f25a76c... Updated Spanish translation (*)
  9f5c581... README schema error documentation and examples (*)
  6aecd74... Fix undefined symbol when id3lib is not available (*)
  dfb03ab... Improve MP4 empty field handling (*)
  ac66630... Use et_str_empty() when writing MP4 tag fields (*)
  3b4766f... Improve MP4 album artist support with newer TagLib (*)
  5182edd... Updated Portuguese translation (*)
  48958f4... Add gettext-domain to GSettings schema (*)
  ddd6fa2... Explicitly mark the GSettings schema for intltool (*)
  9be88c3... Refactor on_picture_add_button_clicked() (*)
  a67b2fa... Refactor and rename ET_Check_If_File_Is_Saved() (*)
  b99d6c7... Improve const use in FLAC and Ogg tagging (*)
  e2c7396... Update version to 2.5.1 on master
  9fe90e1... Mark up a string for translation
  ef72668... Simplify scan dialog capitalization settings

(*) This commit already existed in another branch; no separate mail sent