Migrate to eslint

Summary
We'd like contributors to use the same linter and lint rules that we use
internally.  This diff swaps out eslint for jshint and fixes all lint failures
except for the max-len failures in the test suites.

Test Plan:
- ka-lint src
- make lint
- make test

Reviewers: emily

src/environments.js

@@ -1,3 +1,4 @@
+/* eslint no-constant-condition:0 */
 var fontMetrics = require("./fontMetrics");
 var parseData = require("./parseData");
 var ParseError = require("./ParseError");
@@ -10,7 +11,9 @@ var ParseNode = parseData.ParseNode;
  * with one group per cell.
  */
 function parseArray(parser, result) {
-    var row = [], body = [row], rowGaps = [];
+    var row = [];
+    var body = [row];
+    var rowGaps = [];
     while (true) {
         var cell = parser.parseExpression(false, null);
         row.push(new ParseNode("ordgroup", cell, parser.mode));
@@ -74,7 +77,7 @@ function defineEnvironment(names, props, handler) {
         greediness: 1,
         allowedInText: !!props.allowedInText,
         numOptionalArgs: props.numOptionalArgs || 0,
-        handler: handler
+        handler: handler,
     };
     for (var i = 0; i < names.length; ++i) {
         module.exports[names[i]] = data;
@@ -84,7 +87,7 @@ function defineEnvironment(names, props, handler) {
 // Arrays are part of LaTeX, defined in lttab.dtx so its documentation
 // is part of the source2e.pdf file of LaTeX2e source documentation.
 defineEnvironment("array", {
-    numArgs: 1
+    numArgs: 1,
 }, function(context, args) {
     var colalign = args[0];
     colalign = colalign.value.map ? colalign.value : [colalign];
@@ -93,12 +96,12 @@ defineEnvironment("array", {
         if ("lcr".indexOf(ca) !== -1) {
             return {
                 type: "align",
-                align: ca
+                align: ca,
             };
         } else if (ca === "|") {
             return {
                 type: "separator",
-                separator: "|"
+                separator: "|",
             };
         }
         throw new ParseError(
@@ -108,7 +111,7 @@ defineEnvironment("array", {
     var res = {
         type: "array",
         cols: cols,
-        hskipBeforeAndAfter: true // \@preamble in lttab.dtx
+        hskipBeforeAndAfter: true, // \@preamble in lttab.dtx
     };
     res = parseArray(context.parser, res);
     return res;
@@ -122,7 +125,7 @@ defineEnvironment([
     "bmatrix",
     "Bmatrix",
     "vmatrix",
-    "Vmatrix"
+    "Vmatrix",
 ], {
 }, function(context) {
     var delimiters = {
@@ -131,18 +134,18 @@ defineEnvironment([
         "bmatrix": ["[", "]"],
         "Bmatrix": ["\\{", "\\}"],
         "vmatrix": ["|", "|"],
-        "Vmatrix": ["\\Vert", "\\Vert"]
+        "Vmatrix": ["\\Vert", "\\Vert"],
     }[context.envName];
     var res = {
         type: "array",
-        hskipBeforeAndAfter: false // \hskip -\arraycolsep in amsmath
+        hskipBeforeAndAfter: false, // \hskip -\arraycolsep in amsmath
     };
     res = parseArray(context.parser, res);
     if (delimiters) {
         res = new ParseNode("leftright", {
             body: [res],
             left: delimiters[0],
-            right: delimiters[1]
+            right: delimiters[1],
         }, context.mode);
     }
     return res;
@@ -160,19 +163,19 @@ defineEnvironment("cases", {
             type: "align",
             align: "l",
             pregap: 0,
-            postgap: fontMetrics.metrics.quad
+            postgap: fontMetrics.metrics.quad,
         }, {
             type: "align",
             align: "l",
             pregap: 0,
-            postgap: 0
-        }]
+            postgap: 0,
+        }],
     };
     res = parseArray(context.parser, res);
     res = new ParseNode("leftright", {
         body: [res],
         left: "\\{",
-        right: "."
+        right: ".",
     }, context.mode);
     return res;
 });
@@ -185,7 +188,7 @@ defineEnvironment("aligned", {
 }, function(context) {
     var res = {
         type: "array",
-        cols: []
+        cols: [],
     };
     res = parseArray(context.parser, res);
     var emptyGroup = new ParseNode("ordgroup", [], context.mode);
@@ -211,7 +214,7 @@ defineEnvironment("aligned", {
             type: "align",
             align: align,
             pregap: pregap,
-            postgap: 0
+            postgap: 0,
         };
     }
     return res;