Add a fullscreen button in LastOneLose activity

[llaske]

The idea is to add a fullscreen button in the toolbar to increase the size for activity content on small devices.

The complete process is describe in #399

[pidddgy]

is this really necessary? space already seems to be used pretty well.

[llaske]

See my comment here, you will see a case where just hiding the toolbar without resize give a bad result.

[llaske]

Fixed in 5e2a503