separate deprecated methods

this changes does not break source compatibility,
and fix unnecesary deprecation warnings when using `import Scalaz._`


#### before

```scala
scala> import scalaz._,Scalaz._
import scalaz._
import Scalaz._

scala> 1.wrapNel
warning: there were 1 deprecation warning(s); re-run with -deprecation for details
res0: scalaz.NonEmptyList[Int] = NonEmptyList(1)
```


#### after

```scala
scala> import scalaz._,Scalaz._
import scalaz._
import Scalaz._

scala> 1.wrapNel
res0: scalaz.NonEmptyList[Int] = NonEmptyList(1) // no warnings
```