[easytag] (24 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:

  39497fb... Refactor function to check if all files are saved
  dec23ac... Refactor file list freeing functions
  6ca07ac... Refactor artist album file list functions
  e9f95c4... Remove unused displayed list function
  b99b784... Refactor several file list functions
  c4bbdca... Remove several unused functions
  7edb40e... WIP avoid using filename_to_display()
  16105e4... WIP Avoid using filename_from_display()

Commits added to the branch:

  31b6782... Added German help translation (*)
  c47e1c6... Updated Spanish translation (*)
  7c04a86... Add missing break in switch (*)
  2703196... Remove unnecessary NULL check in CDDB dialog (*)
  65435b7... Fix compilation of misc test (*)
  91e48e8... Handle OptimFrog files as if they are unknown (*)
  2db55ba... Remove redundant declaration (*)
  0a6d022... Add missing default cases in switch statements (*)
  6f19b85... Avoid shadowed variable warnings
  e90a7e8... Avoid unhandled switch cases warning
  9110197... Avoid old-style function declaration
  e0a9c2f... Fix sign comparison warnings
  127157d... Fix const correctness warnings
  3aaf603... Port to AX_COMPILER_FLAGS
  7f2d67b... Use AX_IS_RELEASE to control compiler warnings
  8097699... Use AX_GENERATE_CHANGELOG
  4d2e91f... Refactor function to check if all files are saved
  e9225a1... Refactor file list freeing functions
  f6f2e4d... Refactor artist album file list functions
  e319c90... Remove unused displayed list function
  8a94b7d... Refactor several file list functions
  44ee9ec... Remove several unused functions
  9ff7a13... WIP avoid using filename_to_display()
  fba3796... WIP Avoid using filename_from_display()

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