add animations basics 1-6 (#120)

* add basics

* web: update dependencies

* TransferableTypeData added (#116)

* Updating index with new samples (#121)

* use arrow functions

* remove newline

* use verbs: random*() -> generate*()

* remove <Widget>[] type annotation on lists

* use raised button

* _route() => _createRoute()

* add parameter names to pageBuilder

* use the text theme's display1 for large text

* dispose animation controllers before calling super()

* remove local var

* use raised buttons instead of material buttons

* web: updated dependencies

* Added new test scripts (#122)

* add carousel, card_swipe, and focus_image samples (#119)

* add carousel, card_swipe, and focus_image samples

* fix image assets

* fix more asset images

* add repeating animation

* fix import

* add copyright headers

* remove Center widget

* imageAssetName

* use ClipRect, refactor _SwipeableCardState

* use offset.zero

* add comments

* remove reference to coverflow package

* change spread to toList()

* refactor coverflow sample

don't set width and height
use const
data -> images

* return widget directly, fix formatting

* inline transitionsBuilder

* image -> imageAssetName

* _rectTween() => _createTween()

* _expandToPageRoute -> _createRoute

* move non-updating widgets out of AnimatedBuilder

* code review updates to animations demos

animations/lib/src/basics/02_page_route_builder.dart

@@ -0,0 +1,46 @@
+import 'package:flutter/material.dart';
+
+class PageRouteBuilderDemo extends StatelessWidget {
+  static const String routeName = '/basics/page_route_builder';
+
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(),
+      body: Center(
+        child: RaisedButton(
+          child: Text('Go!'),
+          color: Theme.of(context).primaryColor,
+          onPressed: () {
+            Navigator.of(context).push(_createRoute());
+          },
+        ),
+      ),
+    );
+  }
+}
+
+Route _createRoute() {
+  return PageRouteBuilder(
+    pageBuilder: (context, animation, secondaryAnimation) => _Page2(),
+    transitionsBuilder: (context, animation, secondaryAnimation, child) {
+      var tween = Tween<Offset>(begin: Offset(0.0, 1.0), end: Offset.zero);
+      var curveTween = CurveTween(curve: Curves.ease);
+
+      return SlideTransition(
+        position: animation.drive(curveTween).drive(tween),
+        child: child,
+      );
+    },
+  );
+}
+
+class _Page2 extends StatelessWidget {
+  Widget build(BuildContext context) {
+    return Scaffold(
+      appBar: AppBar(),
+      body: Center(
+        child: Text('Page 2!', style: Theme.of(context).textTheme.display1),
+      ),
+    );
+  }
+}