* Move those fields into their corresponding
TRACKNUMBER/DISCNUMBER/PARTNUMBER fields after parsing so they are
accessible via just one field as PositionInSet which is in line with
other tag formats and also how other software like VLC expect the total
to be specified
* NOT implemented yet: Move those fields optionally back into separate
fields when serializing
This should fix all non-erros, leaving only warnings which
are indeed potential problems.
The following warnings should be safe to ignore:
* Conversions of various offsets from uint64 to
std::streamoff/int64 are safe because such offsets have
been obtained via tellg() and other functions
returning std::streamoff in the first place.
* It also works vice-versa since tellg() should not
return negative offsets with exceptions enabled.
* Conversions from char to unsigned char are also ok.
* Unused diag arguments can be ignored (those might be
useful later).
* Annotate all intended fallthoughs.