code_review: PR #98

* remove the `Leave` option (it may lead to an undefined behaviour), so user can only choose `Stash & reapply` or `Discard`.
* re-design the UI
* remove unused resources

src/Views/Repository.axaml.cs

@@ -298,7 +298,7 @@ namespace SourceGit.Views
                     if (branch.IsCurrent)
                         return;
 
-                    ViewModels.Checkout.ShowPopup(repo, branch.Name);
+                    repo.CheckoutLocalBranch(branch.Name);
                     e.Handled = true;
                 }
             }