Naming slides

[LeonMatthes]

As a presentation creator, I want to be able to name slides in order to easier identify what the slides purpose is.

Acceptance criteria:

• [ ] The slides miniature displays its name
• [ ] The right-click-menu of a slide miniature allows changing of the slides name
• [ ] The slides name is correctly saved when the presentation is filed out

Part of the larger effort to implement #103

Estimated effort: 5