type options = [ `configure | `bmake | `opt | `htdoc ]
type category = [ `base | `godi | `apps | `conf ]
type relop = [ `lt | `gt | `le | `ge | `eq ]
type dep = (category * string * (relop * string) option)
type confopt = {
    name : string;
    default : string;
    description : string;
    implementation : [`makevar of string | `configarg of string];
}