Intermediate: Main Menu

[raybbian]

We need a main menu for our game! For now, this can just be a placeholder UI with a single button for "play", while artists come up with the assets for it.

What you will do

You will likely need to add another game state to our program. It can be something like GameState::MainMenu, which you would add here.

Then, add a system that would render the main menu UI elements, only if the current state is GameState::MainMenu. You might need to modify the run conditions of some other systems so that they don't run while the MainMenu is showing - definitely reach out of you're not sure these ones are!

[awang728]

I would like to do this task