Filters an array or object using only the types allowed. That is, if the item in the array is of a type listed
in the arguments, then it will be added to the filtered array. In this case 'array' is a valid type.
@param {Object} o The object to operate on.
@param {...String} types A list of typeof types that are allowed in the array.
@return {Array<*>} An array filtered by only the allowed types.
function only (o, types) {
                    types = libs.object.toArray(arguments);
                    types.shift();

                    // Allows the 'plural' form of the type...
                    libs.object.each(types, function (type, key) { this[key] = type.replace(/s$/, ''); });

                    if(typeof o !== 'object' || !o) return o;
                    var isArray  = o instanceof Array ? true : false,
                        filtered = isArray ? [] : {},
                        typeArr  = types.indexOf('array'),
                        typeObj  = types.indexOf('object object');

                    libs.object.each(o, function (item, key) {
                        var typeItem = types.indexOf(typeof item);

                        if(typeObj !== -1 && typeArr === -1) {
                            if((typeof item === 'object' && !(item instanceof Array)) || (typeof item !== 'object' && typeItem !== -1)) {
                                if(isArray) filtered.push(item); else filtered[key] = item;
                            }
                        }
                        else if(typeObj !== -1 && typeArr !== -1) {
                            types.push('object');
                            if(typeItem !== -1) {
                                if(isArray) filtered.push(item); else filtered[key] = item;
                            }
                        }
                        else if(typeItem !== -1 || (item instanceof Array && typeArr !== -1)) {
                            if(isArray) filtered.push(item); else filtered[key] = item;
                        }
                    });
                    return filtered;
                }