Textures having png and dds in tree

[Ralph Sennhauser]

Textures under a given name should only have either a png or dds in tree. This currently works as the extension is treated as part of the name. However the engine might gain the ability to fall back to png if dds is not available or similar. Also artist might change one and wonder why there is no effect at all.

binaries/data/mods/public/art/textures/skins/structural/hele_struct_b.dds
binaries/data/mods/public/art/textures/skins/props/cape_hd_black.dds
binaries/data/mods/public/art/textures/skins/props/celt_prop_1.dds
binaries/data/mods/public/art/textures/skins/structural/rome_ram.dds
binaries/data/mods/public/art/textures/terrain/types/desert_forestfloor_palms.dds
binaries/data/mods/public/art/textures/skins/structural/kart_trireme.dds
binaries/data/mods/public/art/textures/skins/structural/iber_struct.dds
binaries/data/mods/public/art/textures/skins/structural/hele_trireme.dds
binaries/data/mods/public/art/textures/skins/props/iber_sail_b.dds
binaries/data/mods/public/art/textures/skins/props/kart_sail_1.dds
binaries/data/mods/public/art/textures/skins/props/kart_sail_2.dds
binaries/data/mods/public/art/textures/skins/props/kart_sail_3.dds
binaries/data/mods/public/art/textures/terrain/types/road_roman.dds
binaries/data/mods/public/art/textures/skins/props/head/celt_caratacos.dds
binaries/data/mods/public/art/textures/skins/skeletal/rome_ijv_e.dds
binaries/data/mods/public/art/textures/skins/skeletal/pers_isp_e_1.dds
binaries/data/mods/public/art/textures/skins/skeletal/mace_bronzeshield_pikeman_a.dds
binaries/data/mods/public/art/textures/skins/gaia/farming_barley_harvest_a.dds
binaries/data/mods/public/art/textures/skins/gaia/farming_wheat_harvest_a.dds
binaries/data/mods/public/art/textures/skins/gaia/farming_wheat_harvest_b.dds
binaries/data/mods/public/art/textures/skins/gaia/tree_cypress_a.dds

[Stan]

In 26054:

Remove duplicate texture hele_struct_b

• Use the correct material, as texture has no alpha, therefore no player color
• Add missing textures where necessary
• Use null_white for hele_blacksmith_bucket_water instead of loading useless textures.

Refs: #6326

[Stan]

In 26057:

Remove duplicate textures.

Refs #6326

[Stan]

In 26058:

Remove duplicate celt_prop_1 texture.

Refs #6326

[Stan]

In 26059:

Remove duplicate dds textures for desert_forestfloor_palms.dds, kart_trireme.dds, tree_cypress_a.dds, farming_wheat_harvest_b.dds, road_roman.dds, celt_caratacos.dds, rome_ijv_e.dds, hele_trireme.dds, iber_sail_b.dds, kart_sail_1.dds, kart_sail_2.dds, kart_sail_3.dds.

Refs #6326

[Stan]

In 26060:

Remove duplicate iber_struct.dds

Fixes #6326