Make all array constructors explicit (#99)

* Make all array constructors explicit

to avoid accidental implicit casts like e.g.
Vector3f v = 0;
assigning nullpointer content.

matrix/Vector3.hpp

@@ -39,7 +39,7 @@ public:
     {
     }
 
-    Vector3(const Type data_[3]) :
+    explicit Vector3(const Type data_[3]) :
         Vector<Type, 3>(data_)
     {
     }