Mp3tag 3.31

What's new in this version:

New:
- added function 'Manage covers...' to cover menu, which allows for adding, removing, replacing, adjusting, and reordering of embedded cover art in one or multiple files
- added advanced tagging option to use single MP4 atom for multiple values
- added support for removing MP3 tag types ID3v1, ID3v2, and APEv2 individually via File List context menu Utils
- added support for removing unsupported fields from MP3 files via File List context menu Utils
- added reset to defaults button to notification configuration options

Changed:
- removed limit to stop after exporting covers with 100 identical names via action export Cover to File.
- preserve selected item when sorting Tag Sources results.
- modernized communication between worker threads and UI.
- symbolic links to folders are not dereferenced in open and save dialogs to more likely preserve user intent and follow platform conventions.
- ensure that files are not read-only before starting the writing process.
- preserve Tag Panel input and File List selection on errors when writing tags
- use copy during drag and drop if that is the only drop method supported by the drag source.
- allow app window to be set as foreground window when launched via context menu from third-party file managers like Total Commander.
- help buttons for option dialogs all open the matching documentation topic
- use `_TAG` as default field name to match all fields for actions Merge duplicate fields and Split field by separator.
- use favorite directory (and Music folder as fallback) as initial directory when changing directory from app temp folder.
- use app temp folder instead of app folder on initial start and if startup directory cannot be accessed.

Fixed:
- file paths were not updated in File List after moving folder and shell returned drive name with lowercase drive letter.
- text in the edit control was not visible when editing directly in the file list and the column width exceeded the visible area.
- runtime error that occurred when attempting to delete a custom list value without a selection.
- dragging and dropping covers from cover window onto themselves either removed or, when Ctrl was pressed, duplicated the cover.
- using `_ALL` as field name in action Split field by separator did not apply the action to all tag fields.
- undefined state in extended tags if next or previous button was clicked while file was being saved.
- LNG: updated Brazilian Portuguese, Catalan, Corsican, Danish, Hungarian, Polish, Russian, Simplified Chinese, Slovak, and Spanish translation