Update all dependencies.

Notably, katex goes from 0.6.0 to 0.16.0 and (for testing purposes
only) markdown-it from 6.0.0 to 13.0.0.  Several tests had to be
updated as katex’s HTML rendering of many math constructs has changed,
but no code changes are required.

Fixes issues waylonflinn#18, waylonflinn#19, waylonflinn#21, waylonflinn#27. Partially addresses waylonflinn#16.
Test cases added.

.gitignore

@@ -1,2 +1,3 @@
-node_modules
-bundle.js
+/bundle.js
+/node_modules
+/package-lock.json

package.json

@@ -22,11 +22,11 @@
   "author": "[email protected]",
   "license": "MIT",
   "dependencies": {
-    "katex": "^0.6.0"
+    "katex": "^0.16.0"
   },
   "devDependencies": {
-    "markdown-it": "^6.0.0",
-    "markdown-it-testgen": "^0.1.4",
-    "tape": "^4.5.1"
+    "markdown-it": "^13.0.0",
+    "markdown-it-testgen": "^0.1.0",
+    "tape": "^5.6.0"
   }
 }

test/all.js

@@ -13,7 +13,9 @@ testLoad(path.join(__dirname, 'fixtures/default.txt'), function(data){
 	data.fixtures.forEach(function (fixture){
 
 		/* generic test definition code using tape */
-		tape(fixture.header, function(t){
+		tape(fixture.header,
+		     { todo: fixture.header.includes(" XFAIL") },
+		     function(t){
 			t.plan(1);
 
 			var expected = fixture.second.text,