Minor fixes regarding introduction of Span<T>.

Author: wo80

CSparse/Storage/CompressedColumnStorage.cs

@@ -309,7 +309,7 @@ public override T[] Row(int rowIndex)
         {
             var target = new T[ColumnCount];
 
-            Row(rowIndex, target);
+            Row(rowIndex, target.AsSpan());
 
             return target;
         }
@@ -343,7 +343,7 @@ public override T[] Column(int columnIndex)
         {
             var target = new T[RowCount];
 
-            Column(columnIndex, target);
+            Column(columnIndex, target.AsSpan());
 
             return target;
         }

CSparse/Storage/DenseColumnMajorStorage.cs

@@ -219,7 +219,7 @@ public override T[] Row(int row)
         {
             var target = new T[columns];
 
-            Row(row, target);
+            Row(row, target.AsSpan());
 
             return target;
         }
@@ -229,7 +229,7 @@ public override T[] Column(int column)
         {
             var target = new T[rows];
 
-            Column(column, target);
+            Column(column, target.AsSpan());
 
             return target;
         }