Add More Example Games

[amiantos]

• adds more default games to the initial state of Gamebook Engine
• adds option to "Add example games" to re-add the default games if you have deleted them or they weren't created somehow

[amiantos]

It'd be nice if that "Add example games" button went to a screen where you could pick which example games you want to add back into the app.

[amiantos]

Merging this in with one new example game