Only prepend the timestamps with \0F if they use formatting

This fixes a bug with fish implementation and append timestamps

src/User.cpp

@@ -525,7 +525,9 @@ CString CUser::AddTimestamp(time_t tm, const CString& sStr) const {
 			// From http://www.mirc.com/colors.html
 			// The Control+O key combination in mIRC inserts ascii character 15,
 			// which turns off all previous attributes, including color, bold, underline, and italics.
-			sRet += "\x0F ";
+			if (sRet.find_first_of("\x02\x03\x04\x0f\x12\x16\x1F")) {
+				sRet += "\x0F ";
+			}
 
 			sRet += sTimestamp;
 		}