refactor

[retrogtx]

Every possible direction (eg: addDirection("crescendo"); ) can be called from a single const now.

The single variable is
const addDirection = (type) => { add('<direction placement="above">'); indent++; add("<direction-type>"); indent++; add(); indent--; add("</direction-type>"); indent--; add("</direction>"); };

Also:

1. Fixes ESLint issues
2. Refactors code to make it concise

[walterbender]

Please add a description for this MR