(INCOMPLETE: ES6 Module conversion and linting)

- Breaking change: Require `new` with `EmbeddedSVGEdit` (allows us to use `class` internally)
- Breaking change: If `svgcanvas.setUiStrings` must now be called if not using editor in order
    to get strings (for sake of i18n) (and if using path.js alone, must also have its `setUiStrings` called)
- Breaking change (ext-overview-window): Avoid global `overviewWindowGlobals`
- Breaking change (ext-imagelib): Change to object-based encoding for namespacing of
    messages (though keep stringifying/parsing ourselves until we remove IE9 support)
- Breaking change: Rename `jquery.js` to `jquery.min.js`
- Breaking change: Remove `scoped` attribute from `style`; it is now deprecated and
    obsolete; also move to head (after other stylesheets)
- Enhancement: Make SpinButton plugin independent of SVGEdit via
    generic state object for tool_scale
- Enhancement: Remove now unused Python l10n scripts (#238)
- Enhancement: ES6 Modules (including jQuery plugins but not jQuery)
- Enhancement: Further JSDoc (incomplete)
- Enhancement (Optimization): Compress images using imageoptim (and add
    npm script) (per #215)
- Fix: i18nize path.js strings and canvas notifications
- Fix: Attempt i18n for ext-markers
- Refactoring (ext-storage): Move locale info to own file imported by the extension (toward modularity; still should be split into separate files by language and *dynamically* imported, but we'll wait for better `import` support to refactor this)
- Refactoring: For imagelib, add local jQuery copy (using old 1.4.4 as had
    been using from server)
- Refactoring: For MathJax, add local copy (using old 2.3 as had been using from
    server); server had not been working
- Refactoring: Remove `use strict` (implicit in modules)
- Refactoring: Remove trailing whitespace, fix some code within comments
- Refactoring: Expect `jQuery` global rather than `$` for better modularity
    (also to adapt line later once available via `import`)
- Refactoring: Prefer `const` (and then `let`)
- Refactoring: Add block scope keywords closer to first block in which they appear
- Refactoring: Use ES6 `class`
- Refactoring `$.isArray` -> `Array.isArray` and avoid some other jQuery core methods
    with simple VanillaJS replacements
- Refactoring: Use abbreviated object property syntax
- Refactoring: Object destructuring
- Refactoring: Remove `uiStrings` contents in svg-editor.js (obtains from locale)
- Refactoring: Add favicon to embedded API file
- Refactoring: Use arrow functions for brief functions (incomplete)
- Refactoring: Use `Array.prototype.includes`/`String.prototype.includes`;
    `String.prototype.startsWith`, `String.prototype.trim`
- Refactoring: Remove now unnecessary svgutils do/while resetting of variables
- Refactoring: Use shorthand methods for object literals (avoid ": function")
- Refactoring: Avoid quoting object property keys where unnecessary
- Refactoring: Just do truthy/falsey check for lengths in place of comparison to 0
- Refactoring (Testing): Avoid jQuery usage within most test files (defer script,
    also in preparation for future switch to ES6 modules for tests)
- Refactoring: Make jpicker variable declaration indent bearable
- Refactoring (Linting): Finish svgcanvas.js
- Docs: Mention in comment no longer an entry file as before
- Docs: Migrate old config, extensions, and FAQ docs
- Licensing: Indicate MIT is license type of rgbcolor; rename/add license file name for
    jgraduate and screencast to reflect type (Apache 2.0); rename file to reflect it
    contains license information (of type MIT) for Raphael icons

editor/extensions/ext-eyedropper.js

@@ -1,5 +1,4 @@
-/* eslint-disable no-var */
-/* globals svgEditor, svgedit, $ */
+/* globals jQuery, svgEditor, svgedit */
 /*
  * ext-eyedropper.js
  *
@@ -16,12 +15,11 @@
 // 4) svgcanvas.js
 
 svgEditor.addExtension('eyedropper', function (S) {
-  'use strict';
-  var // NS = svgedit.NS,
-    // svgcontent = S.svgcontent,
+  const $ = jQuery;
+  const // {svgcontent} = S,
     // svgdoc = S.svgroot.parentNode.ownerDocument,
     svgCanvas = svgEditor.canvas,
-    ChangeElementCommand = svgedit.history.ChangeElementCommand,
+    {ChangeElementCommand} = svgedit.history,
     addToHistory = function (cmd) { svgCanvas.undoMgr.addCommandToHistory(cmd); },
     currentStyle = {
       fillPaint: 'red', fillOpacity: 1.0,
@@ -34,14 +32,14 @@ svgEditor.addExtension('eyedropper', function (S) {
 
   function getStyle (opts) {
     // if we are in eyedropper mode, we don't want to disable the eye-dropper tool
-    var mode = svgCanvas.getMode();
+    const mode = svgCanvas.getMode();
     if (mode === 'eyedropper') { return; }
 
-    var elem = null;
-    var tool = $('#tool_eyedropper');
+    const tool = $('#tool_eyedropper');
     // enable-eye-dropper if one element is selected
+    let elem = null;
     if (!opts.multiselected && opts.elems[0] &&
-      $.inArray(opts.elems[0].nodeName, ['svg', 'g', 'use']) === -1
+      !['svg', 'g', 'use'].includes(opts.elems[0].nodeName)
     ) {
       elem = opts.elems[0];
       tool.removeClass('disabled');
@@ -70,7 +68,7 @@ svgEditor.addExtension('eyedropper', function (S) {
       title: 'Eye Dropper Tool',
       key: 'I',
       events: {
-        click: function () {
+        click () {
           svgCanvas.setMode('eyedropper');
         }
       }
@@ -80,15 +78,15 @@ svgEditor.addExtension('eyedropper', function (S) {
     selectedChanged: getStyle,
     elementChanged: getStyle,
 
-    mouseDown: function (opts) {
-      var mode = svgCanvas.getMode();
+    mouseDown (opts) {
+      const mode = svgCanvas.getMode();
       if (mode === 'eyedropper') {
-        var e = opts.event;
-        var target = e.target;
-        if ($.inArray(target.nodeName, ['svg', 'g', 'use']) === -1) {
-          var changes = {};
+        const e = opts.event;
+        const {target} = e;
+        if (!['svg', 'g', 'use'].includes(target.nodeName)) {
+          const changes = {};
 
-          var change = function (elem, attrname, newvalue) {
+          const change = function (elem, attrname, newvalue) {
             changes[attrname] = elem.getAttribute(attrname);
             elem.setAttribute(attrname, newvalue);
           };