Workaround for specialization issue for known datatypes

specworkaround

import com.azavea.math.Numeric
import com.azavea.math.EasyImplicits._

trait F1[@specialized T, @specialized W] extends Function1[T,W] {
    def apply(a:T):W
 }
abstract class F12D[@specialized T:Numeric:Manifest] extends F1[T,Double]{
  def apply(a:T):Double
}
abstract class F12I[@specialized T:Numeric:Manifest] extends F1[T,Int] {
  def apply(a:T):Int
}
class Bar[@specialized T:Numeric:Manifest] {
  def barToDouble[@specialized S:Numeric:Manifest,W <: F1[T,S]](f:W)=f(numeric[T].zero)
}