Automatic texture compression

[Philip]

See discussion.

• Create a metadata format for expressing DDS compression options.
• Create sensible metadata for each texture currently in the game.
• Create a basic tool for visually testing the compression options.
• Make the engine read the metadata when loading a non-DDS texture, and automatically compress and cache the file on first load.
• Make the release packager perform the compression in advance.
• Make the release packager do XMB and Collada conversions too, and make this conversion pipeline less ad-hoc, and pack everything into a zip.

[Philip]

Also the texture loading system should provide a much more efficient alternative to CTextureEntry::BuildBaseColor.