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

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

base/src/test/user_model/test_rename_sheet.rs

@@ -0,0 +1,39 @@
+#![allow(clippy::unwrap_used)]
+
+use crate::UserModel;
+
+#[test]
+fn basic_rename() {
+    let mut model = UserModel::new_empty("model", "en", "UTC").unwrap();
+    model.rename_sheet(0, "NewSheet").unwrap();
+    assert_eq!(model.get_sheets_info()[0].name, "NewSheet");
+}
+
+#[test]
+fn undo_redo() {
+    let mut model = UserModel::new_empty("model", "en", "UTC").unwrap();
+    model.rename_sheet(0, "NewSheet").unwrap();
+    model.undo().unwrap();
+    assert_eq!(model.get_sheets_info()[0].name, "Sheet1");
+    model.redo().unwrap();
+    assert_eq!(model.get_sheets_info()[0].name, "NewSheet");
+
+    let send_queue = model.flush_send_queue();
+
+    let mut model2 = UserModel::new_empty("model", "en", "UTC").unwrap();
+    model2.apply_external_diffs(&send_queue).unwrap();
+    assert_eq!(model.get_sheets_info()[0].name, "NewSheet");
+}
+
+#[test]
+fn errors() {
+    let mut model = UserModel::new_empty("model", "en", "UTC").unwrap();
+    assert_eq!(
+        model.rename_sheet(0, ""),
+        Err("Invalid name for a sheet: ''.".to_string())
+    );
+    assert_eq!(
+        model.rename_sheet(1, "Hello"),
+        Err("Invalid sheet index".to_string())
+    );
+}