A proper character select

The character selection screen got a rework.

• Icons for each character.
• A row layout that can hold rows of different lengths, centred, which a standard grid can’t do.
• A 3D preview you can handle: drag left and right to spin the character, scroll to zoom in. The zoom moves along the line to the character rather than straight ahead, so the model stays put on screen instead of sliding sideways. Leaving the screen resets the view, so the main menu never shows a character left in an odd pose.