Runtime generation does not take into account static picklers/unpicklers

[jvican]

This is related to #395 but it's not exactly the same. In that example I showed how, when runtime generation is enabled, if there are no picklers/unpicklers for a class A, wrapped by a class W, then a brand new pickler/unpickler for W[A] is created from scratch, without respecting the static picklers/unpicklers available for W.

In this case, I'd like to show that this bug works also the other way around: when we have picklers for Abut not for W.

An example:

case class Map[T, S](s: Spore[T, S])

When asking for the picklers/unpicklers of Map, they are generated in runtime and, consequently, also the runtime picklers/unpicklers for Spore, although we have in scope static picklers/unpicklers for that type. Yet the scala-pickling algorithm should try to find a static pickler for the inner type before generating one.

This only affects scala pickling v0.11.x.