+ Port to scalajs 0.5.4

+ Merge branch 'scala-2.11-scalajs-0.5.x' into scala-2.10-scalajs-0.5.x

Conflicts:
	build.sbt
	examples/src/main/scala/org/parboiled2/examples/Calculator1.scala
	examples/src/main/scala/org/parboiled2/examples/Calculator2.scala