Support nested patchers that look for implicits

[krzemin]

Following this comment, #69 (comment) current implementation of patchers macro doesn't look for loca implicit instances. It neither call itself recursively in order to support following example:

case class Bar(a: Int, b: Boolean)
case class Foo(x: Bar, y: String)

case class BarPatch(a: Int)
case class FooPatch(x: BarPatch)

Foo(Bar(1, true), "test").patchUsing(FooPatch(BarPatch(2))) 
// should be Foo(Bar(5, true), "test")

[MateuszKubuszok]

Depends on #538 which in turns depends on #115.