* tic80.h: Change all the OPERAND defines to use the form (1 << X)

	* tic80.h: Change all the OPERAND defines to use the form (1 << X)
	rather than a constant that is 2**X.  Reorder them to put bits for
	operands that have symbolic names in the upper bits, so they can
	be packed into an int where the lower bits contain the value that
	corresponds to that symbolic name.
	(predefined_symbo): Add struct.
	(tic80_predefined_symbols): Declare array of translations.
	(tic80_num_predefined_symbols): Declare size of that array.
	(tic80_value_to_symbol): Declare function.
	(tic80_symbol_to_value): Declare function.