Fix display of empty tables (#127)

* Fix display of empty tables

Before this patch, empty tables with titles were displayed very "buggy", no titles were shown and only some lines were drawn. With this patch, the titles appear and the body looks empty.

* Fix copy/paste error in test

src/lib.rs

@@ -70,7 +70,10 @@ impl<'a> TableSlice<'a> {
     /// Compute and return the number of column
     // #[deprecated(since="0.8.0", note="Will become private in future release. See [issue #87](https://github.com/phsym/prettytable-rs/issues/87)")]
     fn get_column_num(&self) -> usize {
-        let mut cnum = 0;
+        let mut cnum = match *self.titles {
+            Some(ref t) => t.column_count(),
+            None => 0,
+        };
         for r in self.rows {
             let l = r.column_count();
             if l > cnum {
@@ -986,6 +989,26 @@ mod tests {
         assert_eq!(6, table.print(&mut StringWriter::new()).unwrap());
     }
 
+    #[test]
+    fn test_empty_table_with_title() {
+        let mut table = Table::new();
+        table.set_format(*format::consts::FORMAT_NO_LINESEP_WITH_TITLE);
+
+        table.set_titles(Row::new(vec![Cell::new("Title 1"), Cell::new("Title 2")]));
+
+        let out = "\
++---------+---------+
+| Title 1 | Title 2 |
++---------+---------+
++---------+---------+
+";
+        println!("{}", out);
+        println!("____");
+        println!("{}", table.to_string().replace("\r\n","\n"));
+        assert_eq!(out, table.to_string().replace("\r\n","\n"));
+        assert_eq!(4, table.print(&mut StringWriter::new()).unwrap());
+    }
+
     #[test]
     fn test_horizontal_span() {
         let mut table = Table::new();