Fix tile painter menu

Created by: Exxion

• Adds the N2 decals to the tile painter menu (right after the O2 decals).
• Renames a conflicting icon_state in floors.dmi, thus fixing the icons in the gray category of the tile painter.
  • Luckily, this icon_state was used in exactly one place in all of the code. Updates this, of course.
• Reorders the icons in the tile painter menu for the SS13 and Derelict logos and makes the menu only draw 8 icons per row if the current category is one of those two. This makes the icons form the complete logo in the menu. (Assuming you don't make the menu window tiny so it draws fewer than 8 icons per row, that is.)

Fixes #3318 (closed).