Complete <=1.12 block support

[owengage]

This is a 'super issue' covering all work for pre-flattening blocks.

Feel free to try and knock something off this list!

Blocks in 1.12 and prior are stored with numeric IDs rather than names. For example, blocks with an ID of 3 are dirt blocks. This doesn't fit with the current Chunk and Block in fastanvil. Since 1.12 is no longer receiving updates, we translate the old numeric IDs into their Block equivalents on demand, rather than pollute the current Chunk/Block types with 1.12 logic.

Along with the numeric IDs, there is also 4 extra bits of information called the data value that tell you more about a given block. For example, wooden logs have a numeric ID of 17, and the two smallest bits determine if it is oak, spruce, birch or jungle logs. There is also another wooden log block with ID 162 for the other log types.

Relevant code is in fastanvil/src/java/pre13, in particular the pre13_block_names::modern_block function.

The Minecraft Wiki contains all the necessary information in it's Pre-flattening page.

TODO basics:

• Basic block IDs

TODO Data value extraction:

• Wood Planks
• Stone
• Dirt
• Saplings
• Water and Lava
• Sand
• Wood
• Leaves
• Wool, terracotta, stained Glass and carpet
• Terracotta
• Torches and Redstone Torches
• Slabs
• Fire
• Sandstone
• Red Sandstone
• Beds
• Grass
• Flowers
• Large Flowers
• Piston
• Piston Extension
• Stairs
• Redstone Wire
• Daylight Sensor
• Crops
• Farmland
• Banner
• Door
• Rails
• Ladders, Furnaces, Chests, Trapped Chests
• Sign
• Dispenser and Dropper
• Hopper
• Levers
• Pressure Plates
• Buttons
• Snow
• Cacti and Sugar Canes
• Jukebox
• Pumpkins and Jack o'Lanterns
• Cake
• Redstone Repeater
• Redstone Comparator
• Trapdoors
• Stone Bricks
• Prismarine
• Sponge
• Brown and red mushroom blocks
• Pumpkin stem and Melon stem
• Vines
• Fence Gates
• Nether Wart
• Brewing Stand
• Cauldron
• Nether Portal
• End Portal Frame
• Cocoa
• Tripwire Hook
• Tripwire
• Cobblestone Walls
• Flower Pots
• Heads
• Block of Quartz
• Coal
• Anvil
• Observer
• Maps
• Structure Block
• Chorus Flower
• End Rod
• Glazed Terracotta

[rjp]

Working through some of these. Created a macro for the coloured blocks which seems to work (from some testing in the Rust playground), assuming this is ok?

macro_rules! coloured_block {
    ($a:expr, $b:expr) => {
        {
            let col = match $b & 0b1111 {
                0 => "white",
                1 => "orange",
                2 => "magenta",
                3 => "light_blue",
                4 => "yellow",
                5 => "lime",
                6 => "pink",
                7 => "gray",
                8 => "light_gray",
                9 => "cyan",
                10 => "purple",
                11 => "blue",
                12 => "brown",
                13 => "green",
                14 => "red",
                15 => "black",
                _ => unreachable!(),
            };
            Block {
                name: format!("minecraft:{col}_{}", $a),
                encoded: format!("minecraft:{col}_{}|", $a),
                archetype: BlockArchetype::Normal,
            }
        }
    }
}
// ...
        "carpet" => {
            coloured_block!("carpet", data_value)
        }

[owengage]

Great, I've merged the PR you made and ticked off soem of the things in the list. Cheers!