Fixed viewport calculations for models in menus, and other menu fixes

[MaikelChan]

• The size and position of the viewport in every menu was calculated wrongly. This usually didn't cause issues due to most menus being centered on the screen. But viewport would not fit the size of the menu window depending on the game's resolution. This was noticeable in the character selection in multiplayer menus, as those are not centered.
• Fixed small N64 bug: the red arrows in the character and simulant selection menus were a bit cropped due to the scissor. Now they are a bit more inside the menu window.
• Fixed wrong position of the model in the device training menu, that would offset base on the game's resolution. Also, the position is recalculated every tick so it doesn't break when resizing the game's window while that training menu is open.
• Position is now recalculated every tick too in the character profiles menu.

This fixes this issue, maybe others: #427

[fgsfdsfgs]

Thanks, I've only ever tried to fix the menu model thing for the character bio menu.