Added UNSIGNED-BYTE-8-AREF-AST.
Added UNSIGNED-BYTE-8-ASETF-AST.
Added UNSIGNED-BYTE-8-UNBOX-INSTRUCTION.
Added UNSIGNED-BYTE-8-BOX-INSTRUCTION.
Added UNSIGNED-BYTE-8-AREF-INSTRUCTION.
Added UNSIGNED-BYTE-8-ASET-INSTRUCTION.
Added labels for UNSIGNED-BYTE-8-UNBOX/BOX instructions.