Support Function1 and Function2 methods

[VladUreche]

Function1 provides andThen and composewhile Function2 provides curried and tupled. These should be supported by the function transformation procedure directly, without transforming from MiniboxedFunctionX to FunctionX and then back. Right now, we're safe because anonymous functions are not transformed, but we'll have to do that as part of #114:

$ cat gh-bug-xxx.scala 
package miniboxing.tests.compile.bugxxx

object Test extends App {

  val f = ((x: Int) => x + 1) andThen (x => x * 2)

  println(f(1)) // 4
  println(f(2)) // 6
}

$ mb-scalac gh-bug-xxx.scala -Xprint:interop-commit
[[syntax trees at end of            interop-commit]] // gh-bug-xxx.scala
package miniboxing.tests.compile.bugxxx {
  object Test extends Object with App {
    def <init>(): miniboxing.tests.compile.bugxxx.Test.type = {
      Test.super.<init>();
      ()
    };
    private[this] val f: miniboxing.runtime.MiniboxedFunction1[Int,Int] = MiniboxedFunctionBridge.this.function1_bridge[Int, Int]({
  @SerialVersionUID(value = 0) final <synthetic> class $anonfun extends scala.runtime.AbstractFunction1[Int,Int] with Serializable {
    def <init>(): <$anon: Int => Int> = {
      $anonfun.super.<init>();
      ()
    };
    final def apply(x: Int): Int = x.+(1)
  };
  (new <$anon: Int => Int>(): Int => Int)
}.andThen[Int]({
      @SerialVersionUID(value = 0) final <synthetic> class $anonfun extends scala.runtime.AbstractFunction1[Int,Int] with Serializable {
        def <init>(): <$anon: Int => Int> = {
          $anonfun.super.<init>();
          ()
        };
        final def apply(x: Int): Int = x.*(2)
      };
      (new <$anon: Int => Int>(): Int => Int)
    }));
    <stable> <accessor> def f(): miniboxing.runtime.MiniboxedFunction1[Int,Int] = Test.this.f;
    scala.this.Predef.println(Test.this.f().apply(1));
    scala.this.Predef.println(Test.this.f().apply(2))
  }
}

[VladUreche]

Kicking this down the track, I can't handle it yet.