Merge 2.10.x into master.

Resurrect some undead code from 373ded2ad3 (tuple2Pickler).
Also re-added tests for SI-7183 that I left behind in 664022a30b.

Conflicts:
	src/compiler/scala/tools/nsc/interactive/CompilerControl.scala
	src/compiler/scala/tools/nsc/typechecker/Typers.scala