Basic slice and number_format implementation

[sinasalek]

Here is my small contribution

    Twig.setFilter('slice', function(twig, text, from, to) {
        return text.slice(from, to);
    });
    Number.prototype.format = function(n, x) {
        var re = '\\d(?=(\\d{' + (x || 3) + '})+' + (n > 0 ? '\\.' : '$') + ')';
        return this.toFixed(Math.max(0, ~~n)).replace(new RegExp(re, 'g'), '$&,');
    };
    Twig.setFilter('number_format', function(twig, num) {
        return Number(num).format();
    });