`-P:minibox:Yrewire-functionX-applications` improvements

[VladUreche]

The flag was introduced in https://github.com/miniboxing/miniboxing-plugin/commit/3feb8328e3dab20d05c0cb233e184292c804b3fd but still has some rough edges:

Here goes:

• [x] make it work with 2.10 + make it default
• [ ] split the bridges into fast path / slow path
• [ ] write the fast path in Java, so the vm can easily inline it
• [x] new issue described in the comments

Once these are fixed, make the flag default, so everyone benefits from its magic (see #146 for an example of what I mean by magic).

[VladUreche]

New issue:

$ cat gh-bug-156-issue.scala 
package a

final class Stream[@miniboxed T](val streamf: (T => Boolean) => Unit) {
  def filter(): Stream[T] =
    new Stream(iterf => streamf(value => iterf(value)))
}

$ mb-scalac gh-bug-156-issue.scala 

$ mb-scalac -2.10 gh-bug-156-issue.scala 
gh-bug-156-issue.scala:5: error: [ occured while creating miniboxed method filter in class Stream_D ]
type mismatch;
 found   : miniboxing.runtime.MiniboxedFunction1[Tsp,Boolean]
 required: Tsp => Boolean
    new Stream(iterf => streamf(value => iterf(value)))
                                         ^
one error found

[VladUreche]

Seems the fix broke the build: https://travis-ci.org/miniboxing/miniboxing-plugin/builds/50703046