Different media/tag formats specify languages and countries
differently. This change introduces a Locale class to keep track
of the format being used. So far there are no automatic conversions
implemented so it is entirely up to the user to pass valid values using
a format which matches the one required by the media/tag format.
This change also adds support for Matroska's IETF elements so at least the
raw value can be read, written and is preserved.
1. Convert TYER and related fields of old ID3v2 versions to the new TDRC
field and only expose that via the generic accessors.
2. When writing an old ID3v2 tag, convert TDRC back to the old fields.
3. One can still manually unset the via 1. auto-populated TDRC to disable 2.
and write the old fields directly. So the automatic handling does not
reduce the flexibility of the library.
4. Deprecate 'Year'; it is replaced by the already existing 'RecordDate'
which is now supposed to be used everywhere where 'Year' was used before
5. Introduce 'ReleaseDate' to support this field which is supported in
ID3v2.4.0 and Matroska via the generic accessors.
6. Use ISO format when converting tag values of the type DateTime to/from
string. This is closer to what's used in ID3v2 tags internally. (The
library still allows the old format as fallback when parsing for
compatibility.)
* Close or flush streams explicitely so writing is not
deferred
* to catch errors in the right place
* to avoid suppressing errors completely when writing
would be deferred to the destructor invocation
* Improve comments
Not sure how meta atoms outside of udat are structured. But
the files from my Android camera puts a meta atom directly under
move which doesn't have 4 additional bytes before the first child.