Find and fix reliance on run-time S3TC compression

[Philip Taylor]

When I run on Linux with force_s3tc_enable (without libtxc_dxtn which implements S3TC compression, so I've only got decompression), there's a number of rendering errors that I assume are caused by us attempting to use run-time compression. Need to look in more detail to work out the full list of problems and the exact causes, but I see:

• Some textures are bogus when zoomed out (probably the .dds files are missing mipmaps, and they can't be created dynamically - we ought to ensure all texture files have mipmaps).
• The minimap is entirely black.
• Terrain texture previews in the terrain-picker in Atlas are black.

[Philip Taylor]

See also #439

[(none)]

Milestone Unclassified deleted