(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/contextmenu.js

@@ -1,5 +1,4 @@
-/* eslint-disable no-var */
-/* globals $, svgEditor */
+/* globals jQuery */
 /**
  * Package: svgedit.contextmenu
  *
@@ -9,58 +8,50 @@
  */
 // Dependencies:
 // 1) jQuery (for dom injection of context menus)
-var svgedit = svgedit || {}; // eslint-disable-line no-use-before-define
-(function () {
-var self = this;
-if (!svgedit.contextmenu) {
-  svgedit.contextmenu = {};
-}
-self.contextMenuExtensions = {};
-var menuItemIsValid = function (menuItem) {
+
+const $ = jQuery;
+
+let contextMenuExtensions = {};
+
+const menuItemIsValid = function (menuItem) {
   return menuItem && menuItem.id && menuItem.label && menuItem.action && typeof menuItem.action === 'function';
 };
-var addContextMenuItem = function (menuItem) {
+export const addContextMenuItem = function (menuItem) {
   // menuItem: {id, label, shortcut, action}
   if (!menuItemIsValid(menuItem)) {
     console.error('Menu items must be defined and have at least properties: id, label, action, where action must be a function');
     return;
   }
-  if (menuItem.id in self.contextMenuExtensions) {
+  if (menuItem.id in contextMenuExtensions) {
     console.error('Cannot add extension "' + menuItem.id + '", an extension by that name already exists"');
     return;
   }
   // Register menuItem action, see below for deferred menu dom injection
   console.log('Registed contextmenu item: {id:' + menuItem.id + ', label:' + menuItem.label + '}');
-  self.contextMenuExtensions[menuItem.id] = menuItem;
+  contextMenuExtensions[menuItem.id] = menuItem;
   // TODO: Need to consider how to handle custom enable/disable behavior
 };
-var hasCustomHandler = function (handlerKey) {
-  return self.contextMenuExtensions[handlerKey] && true;
+export const hasCustomMenuItemHandler = function (handlerKey) {
+  return Boolean(contextMenuExtensions[handlerKey]);
 };
-var getCustomHandler = function (handlerKey) {
-  return self.contextMenuExtensions[handlerKey].action;
+export const getCustomMenuItemHandler = function (handlerKey) {
+  return contextMenuExtensions[handlerKey].action;
 };
-var injectExtendedContextMenuItemIntoDom = function (menuItem) {
-  if (Object.keys(self.contextMenuExtensions).length === 0) {
+const injectExtendedContextMenuItemIntoDom = function (menuItem) {
+  if (!Object.keys(contextMenuExtensions).length) {
     // all menuItems appear at the bottom of the menu in their own container.
     // if this is the first extension menu we need to add the separator.
     $('#cmenu_canvas').append("<li class='separator'>");
   }
-  var shortcut = menuItem.shortcut || '';
+  const shortcut = menuItem.shortcut || '';
   $('#cmenu_canvas').append("<li class='disabled'><a href='#" + menuItem.id + "'>" +
     menuItem.label + "<span class='shortcut'>" +
     shortcut + '</span></a></li>');
 };
-// Defer injection to wait out initial menu processing. This probably goes away once all context
-// menu behavior is brought here.
-svgEditor.ready(function () {
-  var menuItem;
-  for (menuItem in self.contextMenuExtensions) {
-    injectExtendedContextMenuItemIntoDom(self.contextMenuExtensions[menuItem]);
+
+export const injectExtendedContextMenuItemsIntoDom = function () {
+  for (const menuItem in contextMenuExtensions) {
+    injectExtendedContextMenuItemIntoDom(contextMenuExtensions[menuItem]);
   }
-});
-svgedit.contextmenu.resetCustomMenus = function () { self.contextMenuExtensions = {}; };
-svgedit.contextmenu.add = addContextMenuItem;
-svgedit.contextmenu.hasCustomHandler = hasCustomHandler;
-svgedit.contextmenu.getCustomHandler = getCustomHandler;
-}());
+};
+export const resetCustomMenus = function () { contextMenuExtensions = {}; };