fix #34806: pedal and other line endpoint calculation improvements

This PR makes some small but significant/important adjustments to the calculation of line segment endpoints in certain cases, as shown in the attached vtests line-2 and line-3 (pedal-1 is an existing test whose behavior is improved as well):

- pedal segments ending in straight (non-angled) hooks now continue for the full duration of the note - almost to the next note or end of measure, just as had already been implemented for pedal segments on a single note - rather than ending after the notehead

- pedal lines that start on a full measure rest now begin with the barline or after the clef / key signature / time signature

- voltas now start after clef / key / time signature if present rather than at the barline

- lines continued across a system break now start after clef / key signature / time signature rather than right on the first chord/rest

- pedal lines continued across a system break and ending with an angle bracket are no longer extended or offset in a way that causes the angle bracket to not align correctly