⌂ Centered measure numbers

Scores of large ensemble works often have bar numbers placed beneath the system, centered horizontally on the measure's extent. This snippet shows how the Measure_counter_engraver may be used to simulate this notational practice. Here, the engraver has been added to a Dynamics context.

This snippet presents a legacy method: starting from LilyPond 2.23.3, \set Score.centerBarNumbers = ##t is enough.