update vexflow from 1.2.93 to 3.0.3: more condensed layout, tremolo slashes start from beginning of stem

#706

package.json

@@ -67,7 +67,7 @@
     "loglevel": "^1.6.8",
     "svg2pdf.js": "^1.5.0",
     "typescript-collections": "^1.3.3",
-    "vexflow": "1.2.93"
+    "vexflow": "3.0.3"
   },
   "devDependencies": {
     "@types/chai": "^4.2.11",