App Menu displays "__main__" as app name immediately after launch

[davidfstr]

Repro Steps A:

• Open an .app version of Crystal (on macOS). The Open or Create Dialog appears.
• Open the "Crystal" menu. Notice that the Hide and Quit menuitems have __main__ as the app name incorrectly.
• Open/create a project.
• Open the "Crystal" menu. Notice that the Hide and Quit menuitems have Crystal as the app name, correctly.
• Close the project. The Open or Create Dialog appears.
• Open the "Crystal" menu. Notice that the Hide and Quit menuitems have Crystal as the app name, correctly.

Repro Steps B (unverified; reconstructed) -- see screenshot below:

• Open an .app version of Crystal (on macOS) using the CLI, and provide a path to a project to open immediately. The Main Window appears.
• Open the "Crystal" menu. Notice that the Hide and Quit menuitems have __main__ as the app name incorrectly.
• Close the project. The Open or Create Dialog appears.
• Open the "Crystal" menu. Notice that the Hide and Quit menuitems have Crystal as the app name, correctly.