remove orphan textures

textures/welcome_block_de_1.png

textures/welcome_block_de_2.png

textures/welcome_block_de_3.png

textures/welcome_block_de_4.png

textures/welcome_block_en_1.png

textures/welcome_block_en_2.png

textures/welcome_block_en_3.png

textures/welcome_block_en_3a.png

textures/welcome_block_en_3b.png

textures/welcome_block_en_4.png