fix #31436: segno et al do not display in mmrest

I copy markers (only) from the first measure of the range to the mmrest.  Elements were already being copied from the last measure.

I also automatically break on non-right-aligned markers (so Segno & Coda automatically start a new mmrest), and check the *previous* measure for jumps & right-aligned markers (so DS & Fine break *after* the measure in which they are placed).