### Features:
+ add update checker
+ add placeholder '{delay:<double>}' for announce type: BOSS_BAR and ACTION_BAR,
it defines the delay time to next text when the next text be displayed.
```yaml
# example
# ...
# delay to next bar is 2s
# default delay time is sets to 0
- '&6progressing boss bar{progress:true}{delay:2}'
# sets segments to 10
# default delay sets to 5 sec
# default color sets to PURPLE
- '&bthe next boss bar{segment:10}'
# ...
```
+ finally, add some newly unknown bugs (may be, XD)