Adding FormulaNode (and demo) with KaTeX and related utilities to pac…

…kage KaTeX. See phetsims/scenery#457

eslint/.eslintrc

@@ -6,12 +6,12 @@
   "extends": "eslint:recommended",
   // The new rules, overrides, etc.
   "rules": {
-    // 
+    //
     // Permit console.log statements (we have a lot of them)
     // TODO: Find a way to make sure no console.log statements make it to production.  Can use the no-console rule
-    // but we want to be able to use console.log during development. 
+    // but we want to be able to use console.log during development.
     "no-console": 0,
-    // 
+    //
     // specify whether backticks, double or single quotes should be used (fixable)
     "quotes": [
       2,
@@ -73,7 +73,7 @@
     //
     // disallow use of assignment in return statement
     "no-return-assign": 2,
-    // 
+    //
     // disallow comparisons where both sides are exactly the same
     "no-self-compare": 2,
     //
@@ -84,7 +84,7 @@
     // disallow use of undefined when initializing variables
     "no-undef-init": 2,
     //
-    // 
+    //
     "require-statement-match": 2,
     // permit only one var declaration per line, see #390
     "one-var": [
@@ -194,6 +194,8 @@
     //For file loading, see SaveLoadNode in Energy Skate Park": Basics
     "FileReader": false,
     "Buffer": false,
+    // For KaTeX
+    "katex": false,
     // For qunit
     "equal": false,
     "test": false