Merge pull request ethereum#3290 from ethereum/moveAppend

Move-append for vector.

libdevcore/CommonData.h

@@ -183,6 +183,12 @@ template <class T, class U> std::vector<T>& operator+=(std::vector<T>& _a, U con
 		_a.push_back(i);
 	return _a;
 }
+/// Concatenate the contents of a container onto a vector, move variant.
+template <class T, class U> std::vector<T>& operator+=(std::vector<T>& _a, U&& _b)
+{
+	std::move(_b.begin(), _b.end(), std::back_inserter(_a));
+	return _a;
+}
 /// Concatenate the contents of a container onto a set
 template <class T, class U> std::set<T>& operator+=(std::set<T>& _a, U const& _b)
 {
@@ -197,6 +203,17 @@ inline std::vector<T> operator+(std::vector<T> const& _a, std::vector<T> const&
 	ret += _b;
 	return ret;
 }
+/// Concatenate two vectors of elements, moving them.
+template <class T>
+inline std::vector<T> operator+(std::vector<T>&& _a, std::vector<T>&& _b)
+{
+	std::vector<T> ret(std::move(_a));
+	if (&_a == &_b)
+		ret += ret;
+	else
+		ret += std::move(_b);
+	return ret;
+}
 
 template <class T, class V>
 bool contains(T const& _t, V const& _v)