darwinop_consts to return a structure and minimize number of left-hand arguments.
refactoring of function get_fields to reduce duplicated code.
move english locale to darwinop_consts_en.
move language selection stuff to darwinop_consts.
refactoring to automatically generate low and high byte fields.
use a structure with named fields rather than an array for translating GUI texts.
separate language constants from other constant values.