protocol: add command "binarylimit"

Increasing the protocol version to 0.22.4 to allow clients to detect
this feature.

Closes https://github.com/MusicPlayerDaemon/MPD/issues/1038

src/client/Client.hxx

@@ -84,6 +84,12 @@ public:
 	 */
 	TagMask tag_mask = TagMask::All();
 
+	/**
+	 * The maximum number of bytes transmitted in a binary
+	 * response.  Can be changed with the "binarylimit" command.
+	 */
+	size_t binary_limit = 8192;
+
 private:
 	static constexpr size_t MAX_SUBSCRIPTIONS = 16;
 
@@ -122,6 +128,7 @@ public:
 	~Client() noexcept;
 
 	using FullyBufferedSocket::GetEventLoop;
+	using FullyBufferedSocket::GetOutputMaxSize;
 
 	gcc_pure
 	bool IsExpired() const noexcept {

src/client/Response.cxx

@@ -59,7 +59,7 @@ Response::Format(const char *fmt, ...) noexcept
 bool
 Response::WriteBinary(ConstBuffer<void> payload) noexcept
 {
-	assert(payload.size <= MAX_BINARY_SIZE);
+	assert(payload.size <= client.binary_limit);
 
 	return Format("binary: %zu\n", payload.size) &&
 		Write(payload.data, payload.size) &&

src/client/Response.hxx

@@ -79,8 +79,6 @@ public:
 	gcc_printf(2,3)
 	bool Format(const char *fmt, ...) noexcept;
 
-	static constexpr size_t MAX_BINARY_SIZE = 8192;
-
 	/**
 	 * Write a binary chunk; this writes the "binary" line, the
 	 * given chunk and the trailing newline.