laydate 日期格式为yyyy 或yyyy-MM时，出现错误Uncaught TypeError: Cannot read property 'length' of undefined

这个改起比较麻烦，没有深究，简单兼容了yyyy 和yyyy-MM，其他格式可能还是会有错误。替换Dates.check方法。

  //检测日期是否合法
  Dates.check = function(){
    var reg = Dates.options.format.replace(/YYYY|MM|DD|hh|mm|ss/g,'\d+\').replace(/\$/g, '');
    var exp = new RegExp(reg), value = Dates.elem[as.elemv];
    var arr = value.match(/d+/g) || [], isvoid = Dates.checkVoid(arr[0], arr[1], arr[2]);
    if(value.replace(/s/g, '') !== ''){
      if(!exp.test(value)){
        Dates.elem[as.elemv] = '';
        Dates.msg('日期不符合格式，请重新选择。');
        return 1;
      } else if(isvoid[0]){
        Dates.elem[as.elemv] = '';
        Dates.msg('日期不在有效期内，请重新选择。');
        return 1;
      } else {
        isvoid.value = Dates.elem[as.elemv].match(exp).join();
        arr = isvoid.value.match(/d+/g);
        if (arr.length > 1) {
            if (arr[1] < 1) {
                arr[1] = 1;
                isvoid.auto = 1;
            } else if (arr[1] > 12) {
                arr[1] = 12;
                isvoid.auto = 1;
            } else if (arr[1].length < 2) {
                isvoid.auto = 1;
            }
        }
        if (arr.length > 2) {
            if (arr[2] < 1) {
                arr[2] = 1;
                isvoid.auto = 1;
            } else if (arr[2] > Dates.months[(arr[1] | 0) - 1]) {
                arr[2] = 31;
                isvoid.auto = 1;
            } else if (arr[2].length < 2) {
                isvoid.auto = 1;
            }
        }
        if(arr.length > 3){
          if(Dates.timeVoid(arr[3], 0)){
            isvoid.auto = 1;
          };
          if(Dates.timeVoid(arr[4], 1)){
            isvoid.auto = 1;
          };
          if(Dates.timeVoid(arr[5], 2)){
            isvoid.auto = 1;
          };
        }
        if(isvoid.auto){
          Dates.creation([arr[0], arr[1]|0, arr[2]|0], 1);
        } else if(isvoid.value !== Dates.elem[as.elemv]){
          Dates.elem[as.elemv] = isvoid.value;
        }
      }
    }
  };