In previous implementation Target provided Keys/SetKeys methods which
allowed working with ECDSA keys. There was also a bug in the NewTargetFromV2
function when the binary key differed in format from the ECDSA key. New
BinaryKeys/SetBinaryKeys methods work with binary keys. To work with ECDSA
keys added functions TargetECDSAKeys/SetTargetECDSAKeys. Old methods are
left and marked deprecated.
Type Record provided an interface for adding a Target by Role and a list of
ECDSA keys. New SetTargets method allows to set the list of Target's,
AddTarget function allows to add a single Target. AddFormedTarget works like
old AddTarget method, which is now deprecated.
Signed-off-by: Leonard Lyubich <leonard@nspcc.ru>
