Further Speed Optimisation

[vzwick]

By pre-caching of $(settings.container) and default_container flag

[vzwick]

The pre-caching should make things significantly faster when using a custom container.

[tuupola]

Thanks. Will merge during weekend.

[tuupola]

Merged half of this. Thanks! Will keep pull request open to remind myself to merge rest of it after I do some internal changes.

[vzwick]

Err. Disregard the update, please.

[regisf]

New update function to improve speed. It's not the jquery way of life, but it's faster. The loop is descending because JIT compiled scripts run faster. Works on FF, Chrome. Not tested with IE.

    function update() {
        var counter = 0;
        for(var i=elements.length - 1; i >= 0; i--) {
            var el = elements[i], $this = $(el);
            if ($this.data('ll_loaded') === true) {
                continue;
            } else if (settings.skip_invisible && !$this.is(':visible')) {
                continue;
            } else if (!$.belowthefold(el, settings) && !$.rightoffold(el, settings)) {
                    $this.trigger("appear");
                    $this.data('ll_loaded', true);
            } else {
                if (++counter > settings.failure_limit) { // Don't know what to do here but it's work.
                    //break;
                    continue
                }
            }
        }
    }