Update tab menu and inventory look (debated making grid system for inventory, but decided it has too many cons [detailed inside])

[kurozael]

In order to compete I considered switching to a grid based inventory system. However, I decided against it because it doesn't really offer any advantage (we could still implement dragging and dropping to craft with the current system), all it does is make restrictions. For example, limitless containers would now be tougher to implement and having too many squares all over the place can be confusing in games with grid inventories. Anyway, I'm gonna update the look of it and keep or refine the Space and Weight system to look nicer visually and to tie in with eachother better.

I'm not gonna try and make this stuff backwards compatible to older schema versions, it's likely schemas will have to be updated to support 0.92.