WiP allow users to give a separate storage that is not the vector_type.

It works but it's probably not respecting the strict aliasing rule.

test/unit/test_custom_storage.cpp

@@ -0,0 +1,52 @@
+/*
+ * Copyright 2015-2017 Michele "King_DuckZ" Santullo
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "vectorwrapper/vectorwrapper.hpp"
+#include <gtest/gtest.h>
+
+namespace {
+	struct VecType {
+		int a, b, c;
+	};
+} //unnamed namespace
+
+namespace vwr {
+	template <>
+	struct VectorWrapperInfo<VecType> {
+		enum { dimensions = 3};
+		typedef int scalar_type;
+		typedef int storage_type[3];
+		enum {
+			offset_x = offsetof(VecType, a),
+			offset_y = offsetof(VecType, b),
+			offset_z = offsetof(VecType, c)
+		};
+	};
+} //namespace vwr
+
+namespace {
+	typedef vwr::Vec<VecType> ivec3;
+} //unnamed namespace
+
+TEST(vwr, custom_storage_type) {
+	ivec3 v(55);
+
+	EXPECT_EQ(v.x(), 55);
+	EXPECT_EQ(v.y(), 55);
+	EXPECT_EQ(v.z(), 55);
+
+	auto& data = v.data();
+}