Astral

Adds new blocks, improve data generation.

Content changes

• Add smooth stone stairs.
• Fixed the mirror's broken model.
• Added log slabs.
• Adjusted item groups for some items.

Internal changes

• Ensure that the texture generator cache works properly.
• Removed data generation classes from final builds.
• Scary method.
• Fixed language file merging during data generation.
• Properly copy images during the texture generation process.