envelop point Y coordinate trees

These trees are built as canonical huffman trees. Remember that negative values are 2's complement encoded and thus appear after the positive values in the trees.

• 0-3: 7 bit
• 4: 5 bits
• 5: 3 bits
• 6: 4 bits
• 7: 1 bits
• 8: 3 bits
• 9: 4 bits
• 10,11: 6 bits
• 12-15: 7 bits

• -8..-5: 9 bits
• -4: 7 bits
• -3: 4 bits
• -2: 2 bits
• -1: 1 bit
• 0: missing
• +1: 3 bits
• +2: 5 bits
• +3: 7 bits
• +4..+7: 9 bits

• -8..-5: 9 bits
• -4: 8 bits
• -3: 7 bits
• -2: 4 bits
• -1: 3 bits
• 0: 1 bit
• +1: 2 bits
• +2: 5 bits
• +3: 8 bits
• +4..+7: 9 bits

• -8..-5: 9 bits
• -4: 7 bits
• -3: 5 bits
• -2: 3 bits
• -1: 3 bits
• 0: 1 bit
• +1: 3 bits
• +2: 4 bits
• +3: 7 bits
• +4..+7: 9 bits