chore(package): update @types/mocha to version 5.2.3 (#279)
chore(package): update @types/mocha to version 5.2.3 (#279)

Closes #223
opensheetmusicdisplay/opensheetmusicdisplay,opensheetmusicdisplay/opensheetmusicdisplay,opensheetmusicdisplay/opensheetmusicdisplay