ClientRead: always ignore whitespace at the end of the line

NEWS

@@ -1,4 +1,6 @@
 ver 0.18.1 (2013/11/??)
+* protocol:
+  - always ignore whitespace at the end of the line
 * filter:
   - autoconvert: fix "volume_normalization" with mp3 files
 * add missing files to source tarball

src/ClientRead.cxx

@@ -21,6 +21,7 @@
 #include "ClientInternal.hxx"
 #include "Main.hxx"
 #include "event/Loop.hxx"
+#include "util/CharUtil.hxx"
 
 #include <assert.h>
 #include <string.h>
@@ -35,11 +36,15 @@ Client::OnSocketInput(void *data, size_t length)
 
 	TimeoutMonitor::ScheduleSeconds(client_timeout);
 
+	BufferedSocket::ConsumeInput(newline + 1 - p);
+
+	/* skip whitespace at the end of the line */
+	while (newline > p && IsWhitespaceOrNull(newline[-1]))
+		--newline;
+
 	/* terminate the string at the end of the line */
 	*newline = 0;
 
-	BufferedSocket::ConsumeInput(newline + 1 - p);
-
 	CommandResult result = client_process_line(*this, p);
 	switch (result) {
 	case CommandResult::OK: