Add Erase(ConstValueIterator) and Erase(ConstValueIterator,ConstValueIterator)

As std::vector::erase() overloads added in C++11

include/rapidjson/document.h

@@ -1008,6 +1008,10 @@ int z = a[0u].GetInt();				// This works too.
 		return Erase(pos, pos + 1);
 	}
 
+	ValueIterator Erase(ConstValueIterator pos) {
+		return Erase(const_cast<ValueIterator>(pos));
+	}
+
 	//! Remove elements in the range [first, last) of the array.
 	/*!
 		\param pos iterator to the element to remove
@@ -1029,6 +1033,10 @@ int z = a[0u].GetInt();				// This works too.
 		return first;
 	}
 
+	ValueIterator Erase(ConstValueIterator first, ConstValueIterator last) {
+		return Erase(const_cast<ValueIterator>(first), const_cast<ValueIterator>(last));
+	}
+
 	//@}
 
 	//!@name Number

test/unittest/valuetest.cpp

@@ -628,11 +628,11 @@ TEST(Value, Array) {
 		x.PushBack(Value(kArrayType).PushBack(i, allocator).Move(), allocator);
 
 	// Erase the first
-	itr = x.Erase(x.Begin());
-	EXPECT_EQ(x.Begin(), itr);
-	EXPECT_EQ(9u, x.Size());
+	itr = x.Erase(y.Begin());	// const iteator is also OK
+	EXPECT_EQ(y.Begin(), itr);
+	EXPECT_EQ(9u, y.Size());
 	for (int i = 0; i < 9; i++)
-		EXPECT_EQ(i + 1, x[i][0u].GetInt());
+		EXPECT_EQ(i + 1, y[i][0u].GetInt());
 
 	// Ease the last
 	itr = x.Erase(x.End() - 1);
@@ -659,7 +659,7 @@ TEST(Value, Array) {
 			for (unsigned i = 0; i < n; i++)
 				x.PushBack(Value(kArrayType).PushBack(i, allocator).Move(), allocator);
 			
-			itr = x.Erase(x.Begin() + first, x.Begin() + last);
+			itr = x.Erase(y.Begin() + first, y.Begin() + last); // const iterator is also OK
 			if (last == n)
 				EXPECT_EQ(x.End(), itr);
 			else