fix problem with alt-drag copying in UScoreView
duplicating UScore should include startTime and track
show TempoMap/BarMap in UScore gui
for now we can change tempo/signature during playback
default tempo becomes 60, 1/4 = 1s
slight improvements on tempo/bar view
force invisible borders in Qt
BarMap no more automatic deleteDuplicates

have to call it explicitly
tweaks to BarMapView
implement tempo locking
add UScoreView.current method

for programming convenience
make UMenuWindow view menu larger
gui tweaks for UChainGUI
more gui tweaks
revisit UScoreView snap behaviour

snap can now be tempoMap aware, and behaves consistently for all event
types. Added a quantize feature, which rounds off all selected events
startTimes to the snap value.
implement arrow keys tempo mapped moving
quantize button quantizes score pos if no events selected
simplify arrow-key moving of events

we can now move all events to the zero line if we keep hitting the left
arrow key.
more elaborate limiting of zero startTime for arrow keys event moving
fix typo