UPDATE: Adds 'user model' API (#27)

* bump version for documentation
* Fixes wrong doc comment
* renames old APIs to be consistent

base/src/test/test_sheet_markup.rs

@@ -21,7 +21,7 @@ fn test_sheet_markup() {
     model.set_cell_style(0, 4, 1, &style).unwrap();
 
     assert_eq!(
-        model.sheet_markup(0),
+        model.get_sheet_markup(0),
         Ok("**Item**|**Cost**\nRent|$600\nElectricity|$200\n**Total**|=SUM(B2:B3)".to_string()),
     )
 }