Merge pull request #199 from ivankravets/patch-12

Build "utility" directory

library.json

@@ -32,7 +32,9 @@
     "examples/*/*/*.ino"
   ],
   "build": {
+    "flags": "-I utility",
     "srcFilter": [
+      "+<utility>",
       "+<*.c>",
       "+<*.cpp>",
       "+<*.h>"