bump MAX_ALLOWED_CIRCULAR_DEPS to 18

- see #236 (comment)

Author: etpinard

tasks/test_syntax.js

@@ -119,7 +119,7 @@ function assertCircularDeps() {
         // as of v1.17.0 - 2016/09/08
         // see https://github.com/plotly/plotly.js/milestone/9
         // for more details
-        var MAX_ALLOWED_CIRCULAR_DEPS = 17;
+        var MAX_ALLOWED_CIRCULAR_DEPS = 18;
 
         if(circularDeps.length > MAX_ALLOWED_CIRCULAR_DEPS) {
             logs.push('some new circular dependencies were added to src/');