Rename rendering/render_*.dart to rendering/*.dart

R=eseidel@chromium.org

Review URL: https://codereview.chromium.org/1166773003

examples/raw/ink_well.dart

@@ -4,8 +4,8 @@
 
 import 'dart:sky' as sky;
 import 'package:sky/framework/app.dart';
-import 'package:sky/framework/rendering/render_box.dart';
-import 'package:sky/framework/rendering/render_node.dart';
+import 'package:sky/framework/rendering/box.dart';
+import 'package:sky/framework/rendering/node.dart';
 import 'package:sky/framework/animation/animated_value.dart';
 import 'package:sky/framework/animation/curves.dart';
 

examples/raw/render_paragraph.dart

@@ -4,10 +4,10 @@
 
 import 'dart:sky';
 import 'package:sky/framework/app.dart';
-import 'package:sky/framework/rendering/render_box.dart';
-import 'package:sky/framework/rendering/render_node.dart';
-import 'package:sky/framework/rendering/render_flex.dart';
-import 'package:sky/framework/rendering/render_paragraph.dart';
+import 'package:sky/framework/rendering/box.dart';
+import 'package:sky/framework/rendering/node.dart';
+import 'package:sky/framework/rendering/flex.dart';
+import 'package:sky/framework/rendering/paragraph.dart';
 
 class RenderSolidColor extends RenderDecoratedBox {
   final Size desiredSize;

examples/raw/sector_layout.dart

@@ -5,8 +5,8 @@
 import 'dart:math' as math;
 import 'dart:sky' as sky;
 import 'package:sky/framework/app.dart';
-import 'package:sky/framework/rendering/render_box.dart';
-import 'package:sky/framework/rendering/render_node.dart';
+import 'package:sky/framework/rendering/box.dart';
+import 'package:sky/framework/rendering/node.dart';
 
 const double kTwoPi = 2 * math.PI;
 

examples/raw/touch_demo.dart

@@ -5,8 +5,8 @@
 import 'dart:math';
 import 'dart:sky';
 import 'package:sky/framework/app.dart';
-import 'package:sky/framework/rendering/render_box.dart';
-import 'package:sky/framework/rendering/render_node.dart';
+import 'package:sky/framework/rendering/box.dart';
+import 'package:sky/framework/rendering/node.dart';
 
 // Material design colors. :p
 List<int> colors = [