XiaoMigros

Thanks @Jojo-Schmitz for finding the places for slurs and glissandos! I agree that autoplace is a different issue, since this PR currently only changes the visual rendering of the elements...

Guitar bends seem fine in master (both visibility and color)

My understanding would be `PropertyValue::fromValue(item->getProperty(Pid::COLOR))`

I wouldn't be so keen on changing the actual default positioning, but perhaps a sensible reposition can be calculated when first being added to the score.

Maybe the measure should not automatically appear, but rather the cursor move past the last barline? That way, if another note is inputted the measure will be added, but if...

I'm wondering what the best way to solve this would be... A toggle in properties for horizontal frames "Display courtesy keysig, timesig, clef in previous measure" ?

Even when the new measure is on the same system? Because there I would argue it shouldn't be the default, but the user should still have control over whether to...

Section breaks won't work in cases like this... 

Yes, system break on a horizontal frame, which is only one of the many use cases

Well, yes. However since there are other instances where different behavior could be wanted, I think a more encompassing solution is best (see my example above)