codec: remove redundant checks for hasLen and decContainerLen, and decodeValue handles TryNil for any value.
codec: remove redundant checks for hasLen and decContainerLen, and decodeValue handles TryNil for any value.

Handle TryNil well in decodeValue, to be used for any value, not just pointers.

ugorji/go,ugorji/go,ugorji/go