Explicit default Matrix constructor.

Nothing like this should ever happen:

    1*Vector3::yAxis() // 1 converted to true, converted to Matrix3.

src/Math/Matrix.h

@@ -56,7 +56,7 @@ template<class T, size_t size> class Matrix {
          * @brief Default constructor
          * @param identity Create identity matrix instead of zero matrix.
          */
-        inline Matrix(bool identity = true): _data() {
+        inline explicit Matrix(bool identity = true): _data() {
             /** @todo constexpr how? */
             if(identity) for(size_t i = 0; i != size; ++i)
                 _data[size*i+i] = static_cast<T>(1);

src/Math/Matrix3.h

@@ -38,7 +38,7 @@ template<class T> class Matrix3: public Matrix<T, 3> {
         }
 
         /** @copydoc Matrix::Matrix(bool) */
-        inline constexpr Matrix3(bool identity = true): Matrix<T, 3>{
+        inline constexpr explicit Matrix3(bool identity = true): Matrix<T, 3>{
             /** @todo Make this in Matrix itself, after it will be constexpr */
             identity ? 1.0f : 0.0f, 0.0f, 0.0f,
             0.0f, identity ? 1.0f : 0.0f, 0.0f,

src/Math/Matrix4.h

@@ -106,7 +106,7 @@ template<class T> class Matrix4: public Matrix<T, 4> {
         }
 
         /** @copydoc Matrix::Matrix(bool) */
-        inline constexpr Matrix4(bool identity = true): Matrix<T, 4>{
+        inline constexpr explicit Matrix4(bool identity = true): Matrix<T, 4>{
             /** @todo Make this in Matrix itself, after it will be constexpr */
             identity ? 1.0f : 0.0f, 0.0f, 0.0f, 0.0f,
             0.0f, identity ? 1.0f : 0.0f, 0.0f, 0.0f,