[forms] new optional suffix attribute on widget objects, used to generage input name / dom id. Ease reuse of widgets from another widget. Also move base values computing to a separated values(form, field) method.

function set_tab(tabname, cookiename) {
    // set appropriate cookie
    asyncRemoteExec('set_cookie', cookiename, tabname);
    // trigger show + tabname event
    trigger_load(tabname);
}