WIP-MEI: Fixed: All ___fromElement() Functions Accept a "slurBundle" Parameter

This will yield simpler code, since we won't have to think about which functions
do and do not accept two arguments. We'll make it simple: they all do.
WIP-MEI: Fixed: Simplifications promised in the previous commit
WIP-MEI: Fixed: All the debugging output uses environLocal.printDebug()
WIP-MEI: Testing: Update the noteFromElement() Tests

This accounts for handling the @tie attribute. It doesn't yet test
slur-handling.
WIP-MEI: Testing: Update chordFromElement() Tests

This accounts for the @tie attribute and recent articulation fixes, but not
slur handling.
WIP-MEI: Testing: Update layerFromElement() Tests

Now they accept the fact that everything gets called with the slurBundle
WIP-MEI: Tests: Update staffFromElement() Tests

Now the mock layerFromElement() accepts the "slurBundle" kwarg.