manage loading status view
usage:
//if set true, logs will print into logcat
Gloading.debug(trueOrFalse);
//init the default loading status view creator (
Gloading.Adapter)
Gloading.initDefault(adapter);
//wrap an activity. return the holder
Holder holder = Gloading.getDefault().wrap(activity);
//wrap an activity and set retry task. return the holder
Holder holder = Gloading.getDefault().wrap(activity).withRetry(retryTask);
//wrap a view and set retry task. return the holder
Holder holder = Gloading.getDefault().wrap(view).withRetry(retryTask);
//cover a view which relatives to another view within a parent of RelativeLayout or ConstraintLayout parent
Holder holder = Gloading.getDefault().cover(view).withRetry(retryTask);
holder.showLoading() //show loading status view by holder
holder.showLoadSuccess() //show load success status view by holder (frequently, hide gloading)
holder.showFailed() //show load failed status view by holder (frequently, needs retry task)
holder.showEmpty() //show empty status view by holder.