Add option to preserve tags 100% / preserve custom tag fields

[Gorrrg]

Is your feature request related to a problem? Please describe. Custom tags fields get renamed or purged, when transconding from the same format. This breaks how I made albums be presented in foobar2000.

fre:ac also removes TRACK=0 or TRACK=00! (I use it for Hidden Track One Audio files).

before:

after:

Describe the solution you'd like Just copy the tags 1:1 when transcoding from FLAC to FLAC, WavPack to WavPack, MP3 to MP3, etc. When transcoding to a different (tag) format use the same translation mechanisms as Mp3Tag or similar taggers. Also there's no way to omit the addition of the ENCODER tag field, at least I haven't found an option to disable it.

Describe alternatives you've considered Not using fre:ac and use an ancient single-threaded DOS batch script and command line tools that preserve tags.