Add basic main menu UI

[surrsurus]

Ties into #47 as screens will be necessary to complete.

The goal is to have some sort of navigable main menu screen, but how is this to be done? The simplest answer is to have the Engine update Screens in the Renderer and have the Engine capture input of the player navigating around the options. I think its possible to have:

• Name entry
• Race selection (Which raises the question of lore)

at the very minimum to prove this is possible.

[surrsurus]

Requesting that @sudo-prime can help with designing

• Mockups
• Basic implementation plan