Minor adaptivity issues

[turtlegarden]

Right now, Biblioteca has some minor issues with screen size:

• The tab overview cannot be triggered with a shortcut
• If the window size is expanded, the overview is still shown
• The sidebar is not opened when F10 is pressed to activate the menu
• The sidebar cannot be toggled with a shortcut

I have a branch where I am fixing all of these things, and all but the last are fixed. I would also reccomend adding a button to open the overview in large window mode, somewhat like how GNOME Web does it with a button in the header bar that can trigger it, as the overview is useful to desktop users as well or people who have many tabs open.

[turtlegarden]

closed with merge of #71