⌂ Accordion-discant symbols

This snippet has been obsoleted by predefined markup commands, see 'Discant symbols' in the Notation Reference. It's still useful as a simple demonstration of how to combine symbols: the placement of the symbols added with \markup can be tweaked by changing the \translate-scaled arguments. \translate-scaled is used here rather than \translate in order to let the positioning of the symbol parts adapt to changes of font-size.