95% Phonics Menu Hider

Adds a button to hide the menu and skips the saved slide dialog on 95% phonics.

A low-impact extension that adds an additional button to the 95% Phonics Core program presentation documents that allows the side-menu to be hidden when using the presentation in full-screen mode. The addon also automatically sets the presentation to open on the last-used page, rather than prompting the user every time. Since the menu is left open until the user selects to hide it, resetting the presentation through the menu instead of the pop-up dialog does not add any additional clicks but does reduce the barrier to starting work in the majority of use cases.