Update buffer_write and vector_write (#809)

buffer.h

@@ -22,7 +22,7 @@ inline void buffer_write_block(unsigned char*& p, const void* src, size_t size)
 	p += size;
 }
 template<typename T>
-inline void buffer_write(unsigned char*& p, T value) {
+inline void buffer_write(unsigned char*& p, const T& value) {
 	std::memcpy(p, &value, sizeof(T));
 	p += sizeof(T);
 }
@@ -30,10 +30,10 @@ inline void buffer_write(unsigned char*& p, T value) {
 inline void vector_write_block(std::vector<unsigned char>& buffer, const void* src, size_t size) {
 	const auto len = buffer.size();
 	buffer.resize(len + size);
-	std::memcpy(&buffer[len], src, size);
+	std::memcpy(buffer.data() + len, src, size);
 }
 template<typename T>
-inline void vector_write(std::vector<unsigned char>& buffer, T value) {
+inline void vector_write(std::vector<unsigned char>& buffer, const T& value) {
 	vector_write_block(buffer, &value, sizeof(T));
 }