close #511810: bad rql generated when looking for vocabulary for a relation on an entity which doesn't exist (yet) technical details: * add a graph of linked variables in the RRQLExpression instance * modify rql rewriter to remove relations where an unexistant variable and or a variable linked to an unexistant variable is used. * activate this feature in Entity.unrelated_rql if the entity doesn't exists yet

function load_now(eltsel, holesel, reloadable) {
    var lazydiv = jQuery(eltsel);
    var hole = lazydiv.children(holesel);
    if ((hole.length == 0) && !reloadable) {
	/* the hole is already filled */
	return;
    }
    lazydiv.loadxhtml(lazydiv.attr('cubicweb:loadurl'));
}

function trigger_load(divid) {
    jQuery('#lazy-' + divid).trigger('load_' + divid);
}