fix TextLoader bug when there's newline between quotes

src/Microsoft.ML.Data/DataLoadSave/Text/TextLoaderCursor.cs

@@ -487,7 +487,7 @@ private void ThreadProc()
                                     // REVIEW: Avoid allocating a string for every line. This would probably require
                                     // introducing a CharSpan type (similar to ReadOnlyMemory but based on char[] or StringBuilder)
                                     // and implementing all the necessary conversion functionality on it. See task 3871.
-                                    text = rdr.ReadLine();
+                                    text = rdr.ReadEntry();
                                     if (text == null)
                                         goto LNext;
                                     line++;
@@ -514,7 +514,7 @@ private void ThreadProc()
                                     if (_abort)
                                         return;
 
-                                    text = rdr.ReadLine();
+                                    text = rdr.ReadEntry();
                                     if (text == null)
                                     {
                                         // We're done with this file. Queue the last partial batch.

src/Microsoft.ML.Data/Utilities/StreamUtils.cs

@@ -174,5 +174,39 @@ private static string[] Expand(string pattern)
             return matchList.ToArray();
         }
 #endif
+
+        public static string ReadEntry(this TextReader sr)
+        {
+            string entry = string.Empty;
+
+            // get first bit
+            entry += sr.ReadLine();
+
+            // And get more lines until the number of quotes is even
+            while (GetNumberOf(entry, "\"") % 2 != 0 )
+            {
+                string line = sr.ReadLine();
+                entry += line;
+            }
+
+            // Then return what we've gotten
+            if (entry == string.Empty)
+            {
+                return null;
+            }
+            else
+            {
+                return entry;
+            }
+        }
+
+        public static int GetNumberOf(string s, string strSearchString)
+        {
+            if(strSearchString.Length == 0 || s.Length == 0)
+            {
+                return 0;
+            }
+            return (s.Length - s.Replace(strSearchString, string.Empty).Length) / strSearchString.Length;
+        }
     }
 }