Added CUDA Compatible slicing

Array.h

@@ -32,7 +32,13 @@ template <typename T> struct EigenAdaptConst_S<const T> { typedef ConstEigenMapM
 template <typename T> using EigenAdaptConst = typename EigenAdaptConst_S<T>::type;
 
 template <typename T> class Array;
-using Slice = std::pair<uint32_t, uint32_t>;
+
+struct Slice {
+    uint32_t first;
+    uint32_t second;
+    HD Slice(const std::initializer_list<uint32_t> i)
+        : first(*i.begin()), second(*(i.begin() + 1)) {}
+};
 
 template <typename T> class ArrayIterator {
   private: