[easytag] (18 commits) Non-fast-forward update to branch wip/help

[David King <davidk src gnome org>]

The branch 'wip/help' 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:

  6121add... Add help page on Ogg tag splitting
  5f605ae... Update help now that MP4 cover art is supported

Commits added to the branch:

  46a2208... Move file type table contents (*)
  df33e49... Fix ETFileDescription length (*)
  4d0d294... Update NEWS for 2.1.10.99 preview release (*)
  70a8891... Use C++ TagLib API for MP4 tags
  dd2ce06... Detect good set of warning flags for C++ compiler
  e23ea39... Support extended fields for MP4 tags
  db6d501... Implement cover art support for MP4
  e561c91... Support album artist in MP4 files
  30798d6... Use C++ TagLib API for MP4 header information
  44ee383... Add GIO/TagLib compatibility layer
  3a53d41... Use GIO wrappers in mp4_tag.cc
  3b3f81a... Use GIO wrappers in mp4_header.cc
  0bf00a1... Improve error handling in GIO/TagLib wrapper
  0955b0b... Add basic error reporting to mp4_tag.cc
  e776981... Add basic error reporting to mp4_header.cc
  f5957ed... Remove auto pointer template
  7803968... Update help now that MP4 cover art is supported
  b8e4bf4... Add help page on Ogg tag splitting

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