Introduces select-kit

* renames `select-box-kit` into `select-kit`
* introduces `single-select` and `multi-select` as base components
* introduces {{search-advanced-category-chooser}} as a better component for selecting category in advanced search
* improves events handling in select-kit
* recreates color selection inputs using {{multi-select}} and a custom {{selected-color}} component
* replaces category-selector by a component using select-kit and based on multi-select
* improves positioning of wrapper
* removes the need for offscreen, and instead use `select-kit-header` as a base focus point for all select-kit based components
* introduces a formal plugin api for select-kit based components
* introduces a formal pattern for loading and updating select-kit based components:

```
computeValue()
computeContent()
mutateValue()
```

test/javascripts/widgets/actions-summary-test.js.es6

@@ -74,7 +74,7 @@ widgetTest('post deleted', {
     });
   },
   test(assert) {
-    assert.ok(this.$('.post-action .d-icon-trash-o').length === 1, 'it has the deleted icon');
+    assert.ok(this.$('.post-action .d-trash-o').length === 1, 'it has the deleted icon');
     assert.ok(this.$('.avatar[title=eviltrout]').length === 1, 'it has the deleted by avatar');
   }
 });

test/javascripts/widgets/button-test.js.es6

@@ -11,7 +11,7 @@ widgetTest('icon only button', {
 
   test(assert) {
     assert.ok(this.$('button.btn.btn-icon.no-text').length, 'it has all the classes');
-    assert.ok(this.$('button .d-icon.d-icon-smile-o').length, 'it has the icon');
+    assert.ok(this.$('button .d-icon.d-smile-o').length, 'it has the icon');
   }
 });
 
@@ -24,7 +24,7 @@ widgetTest('icon and text button', {
 
   test(assert) {
     assert.ok(this.$('button.btn.btn-icon-text').length, 'it has all the classes');
-    assert.ok(this.$('button .d-icon.d-icon-plus').length, 'it has the icon');
+    assert.ok(this.$('button .d-icon.d-plus').length, 'it has the icon');
     assert.ok(this.$('button span.d-button-label').length, 'it has the label');
   }
 });

test/javascripts/widgets/home-logo-test.js.es6

@@ -66,7 +66,7 @@ widgetTest('no logo - minimized', {
   },
 
   test(assert) {
-    assert.ok(this.$('.d-icon-home').length === 1);
+    assert.ok(this.$('.d-home').length === 1);
   }
 });
 

test/javascripts/widgets/post-test.js.es6

@@ -436,7 +436,7 @@ widgetTest("reply directly above", {
     click('a.reply-to-tab');
     andThen(() => {
       assert.equal(this.$('section.embedded-posts.top .cooked').length, 1);
-      assert.equal(this.$('section.embedded-posts .d-icon-arrow-up').length, 1);
+      assert.equal(this.$('section.embedded-posts .d-arrow-up').length, 1);
     });
   }
 });
@@ -673,7 +673,7 @@ widgetTest("replies - one below, not suppressed", {
     click('button.show-replies');
     andThen(() => {
       assert.equal(this.$('section.embedded-posts.bottom .cooked').length, 1);
-      assert.equal(this.$('section.embedded-posts .d-icon-arrow-down').length, 1);
+      assert.equal(this.$('section.embedded-posts .d-arrow-down').length, 1);
     });
   }
 });
@@ -760,7 +760,7 @@ widgetTest("topic map - links", {
     click('nav.buttons button');
     andThen(() => {
       assert.equal(this.$('.map.map-collapsed').length, 0);
-      assert.equal(this.$('.topic-map .d-icon-chevron-up').length, 1);
+      assert.equal(this.$('.topic-map .d-chevron-up').length, 1);
       assert.equal(this.$('.topic-map-expanded').length, 1);
       assert.equal(this.$('.topic-map-expanded .topic-link').length, 5, 'it limits the links displayed');
     });

test/javascripts/widgets/poster-name-test.js.es6

@@ -38,7 +38,7 @@ widgetTest('extra classes and glyphs', {
     assert.ok(this.$('span.staff').length);
     assert.ok(this.$('span.admin').length);
     assert.ok(this.$('span.moderator').length);
-    assert.ok(this.$('.d-icon-shield').length);
+    assert.ok(this.$('.d-shield').length);
     assert.ok(this.$('span.new-user').length);
     assert.ok(this.$('span.fish').length);
   }