Revert "skip of table header in MLData (#1962)"

This reverts commit 4d36be8794.

Conflicts:
	modules/ml/include/opencv2/ml/ml.hpp
	modules/ml/src/data.cpp

modules/ml/src/data.cpp

@@ -71,7 +71,6 @@ CvMLData::CvMLData()
 {
     values = missing = var_types = var_idx_mask = response_out = var_idx_out = var_types_out = 0;
     train_sample_idx = test_sample_idx = 0;
-	header_lines_number = 0;
     sample_idx = 0;
     response_idx = -1;
 
@@ -118,17 +117,6 @@ void CvMLData::clear()
     train_sample_count = -1;
 }
 
-
-void CvMLData::set_header_lines_number( int idx )
-{
-	header_lines_number = (short)std::max(0, idx);
-}
-
-int CvMLData::get_header_lines_number() const
-{
-	return header_lines_number;
-}
-
 static char *fgets_chomp(char *str, int n, FILE *stream)
 {
 	char *head = fgets(str, n, stream);
@@ -165,15 +153,9 @@ int CvMLData::read_csv(const char* filename)
     if( !file )
         return -1;
 
-	std::vector<char> _buf(M);
+    // read the first line and determine the number of variables
+    std::vector<char> _buf(M);
     char* buf = &_buf[0];
-    
-	// skip header lines
-	for( int i = 0; i < header_lines_number; i++ )
-		if( fgets( buf, M, file ) == 0 )
-			return -1;
-
-    // read the first data line and determine the number of variables
     if( !fgets_chomp( buf, M, file ))
     {
         fclose(file);