Add SVGLint (#922)

* Added SVGLint

* Added SVGLint to CI

* Upgraded Node version used by CI

* Upgraded SVGLint to latest version

* Moved SVGLint configuration file

* Upgraded SVGLint

1.0.1 -> 1.0.2
Adds support for globs on Windows

* Added SVGLint check for aria-labelledby and title ID

.svglintrc.js

@@ -0,0 +1,41 @@
+module.exports = {
+    rules: {
+        elm: {
+            "svg": 1,
+            "svg > title": 1,
+            "g": false,
+        },
+        attr: [
+            { // ensure that the SVG elm has the appropriate attrs
+                "aria-labelledby": /^simpleicons-.+-icon$/,
+                "role": "img",
+                "viewBox": "0 0 24 24",
+                "xmlns": "http://www.w3.org/2000/svg",
+
+                "rule::selector": "svg",
+                "rule::whitelist": true,
+            },
+            { // ensure that the title elm has the appropriate attr
+                "id": /^simpleicons-.+-icon$/,
+
+                "rule::selector": "svg > title",
+                "rule::whitelist": true,
+            }
+        ],
+        custom: [
+            // ensure that aria-labelledby and id match
+            function checkValidAria(reporter, $, ast) {
+                const labelledByValue = $.find("svg").attr("aria-labelledby");
+                const $title = $.find("svg > title");
+                const titleIdValue = $title.attr("id");
+                if (labelledByValue !== titleIdValue) {
+                    reporter.error(
+                        `'aria-labelledby' and 'id' should match, were '${labelledByValue}' and '${titleIdValue}'`,
+                        $title[0],
+                        ast
+                    );
+                }
+            }
+        ]
+    }
+};

.travis.yml

@@ -2,10 +2,11 @@ matrix:
   include:
     - language: node_js
       node_js:
-        - "6"
+        - "8"
 
       script:
         - npm run jsonlint
+        - npm run svglint
 
       notifications:
         email: