TE: erased textures on rooms rotation

[LoreRaider]

When rotating a room, some textures gets erased from the extra walls segments of a floor or ceiling, so anything below E-D line and anything above R-F line

Repro steps:

• Raise/lower a floor/ceiling and add wall segments
• Texture the segments
• Rotate the room via Rooms->Transform rooms-> Rotate rooms clockwise

Result: