mtest 0.7.1

• mcpplibs.mtest.e2e, .bench and .cts are public modules of the library. Each re-exports
  mcpplibs.mtest, so the lib root cannot re-export them, and a program that imported one was told
  that it was not public and would fail against the packed library (mcpp SPEC-008). Each is now a
  feature, on by default (e2e, bench, cts), which is how mcpp counts a module beside the root
  as public; a program's imports and its manifest are unchanged.