Add `// V2 format` comment to V2 specific code
in contracts. In `subnet` contract change comment
to sync with other.
Signed-off-by: Pavel Karpy <carpawell@nspcc.ru>
Unified format uses transfer type as the first byte
and extra details next. List of transfer types used in
contracts defined in `transfer.go`. It includes:
- mint,
- burn,
- lock,
- unlock,
- container fee.
Signed-off-by: Alex Vanin <alexey@nspcc.ru>
