Add missing attributes to operators

Context

For some operators, not all ONNX supported attributes were added to Aidge. This MR is dedicated to complete those operators:

• Reshape: add 'allowzero' attribute
• Slice: add 'steps' input

Fixes a part of Issue_70 and Issue_10

Modified files

• Reshape.hpp, Reshape.cpp and pybind_Reshape.cpp, add 'allowzero' attribute to Reshape operator;
• Slice.hpp, Slice.cpp and pybind_Slice.cpp, add 'steps' attribute to Slice operator;

TODO

• Add all Reshape attributes
• Add all Slice attributes

include/aidge/operator/Reshape.hpp

@@ -29,24 +29,25 @@ public:
     void forward() override;
 };
 
-enum class ReshapeAttr { Shape };
+enum class ReshapeAttr { Shape, AllowZero };
 
 class Reshape_Op : public OperatorTensor,
                    public Registrable<Reshape_Op, std::string, std::shared_ptr<OperatorImpl>(const Reshape_Op&)>,
-                   public StaticAttributes<ReshapeAttr, std::vector<std::int64_t>> {
+                   public StaticAttributes<ReshapeAttr, std::vector<std::int64_t>, bool> {
 
 public:
     static const std::string Type;
 
     Reshape_Op() = delete;
 
-    using Attributes_ = StaticAttributes<ReshapeAttr, std::vector<std::int64_t>>;
+    using Attributes_ = StaticAttributes<ReshapeAttr, std::vector<std::int64_t>,  bool>;
     template <ReshapeAttr e>
     using attr = typename Attributes_::template attr<e>;
 
-    Reshape_Op(const std::vector<std::int64_t>& shape)
+    Reshape_Op(const std::vector<std::int64_t>& shape, bool allowzero)
         : OperatorTensor(Type, 2, 0, 1),
-          Attributes_(attr<ReshapeAttr::Shape>(shape))
+          Attributes_(attr<ReshapeAttr::Shape>(shape),
+                      attr<ReshapeAttr::AllowZero>(allowzero))
     {
         mImpl = std::make_shared<Reshape_OpImpl>(*this);
     }
@@ -89,15 +90,16 @@ public:
 };
 
 inline std::shared_ptr<Node> Reshape(const std::vector<std::int64_t>& shape = {},
-                                   		const std::string &name = "") {
+                                     bool allowzero = false,
+                                   	 const std::string &name = "") {
     // FIXME: properly handle default w&b initialization in every cases
-    return std::make_shared<Node>(std::make_shared<Reshape_Op>(shape), name);
+    return std::make_shared<Node>(std::make_shared<Reshape_Op>(shape, allowzero), name);
 }
 }  // namespace Aidge
 
 namespace {
 template <>
-const char *const EnumStrings<Aidge::ReshapeAttr>::data[] = { "Shape" };
+const char *const EnumStrings<Aidge::ReshapeAttr>::data[] = { "Shape", "AllowZero" };
 }
 
 #endif /* AIDGE_CORE_OPERATOR_RESHAPE_H_ */