Two new tests: tst_concertpitchbenchmark and tst_keysig

mtest/libmscore/concertpitch/tst_concertpitchbenchmark
this test loads a score containing 6 transposing instruments, 216 measures and a total of 5184 notes. The test changes to concert pitch, relayouts, changes back and relayouts.

mtest/libmscore/keysig/tst_keysig
this loads a score, adds, changes and removes a key signature in measure 2 and checks, if accidentals of notes starting with measure 2 are updated according to the new key signature. These three steps are then undone, also checking the updates after each undo step.