moved matrix class from utils to samples

utils/matrix/float32.dart

-// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-
-/**
- * Emulates the browser's Float32Array (so Matrix4 can be used outside
- * the browser.
- * (Note this stores entries as 64-bit doubles, since there is no
- * 32-bit float type on the vm.)
- */
-class Float32Array {
-  final List<double> buf;
-
-  Float32Array(int size) : buf = new List<double>(size) {
-    for (int i = 0; i < size; i++) {
-      buf[i] = 0.0;
-    }
-  }
-
-  double operator [](int i) {
-    return buf[i];
-  }
-
-  void operator []=(int i, num value) {
-    buf[i] = (value != null) ? value.toDouble() : 0.0;
-  }
-}