improved the User Interface.

[inherithandle]

• the "Select All/ Unselect all items" button.
  • it is not fair to type javascript:document.querySelectorAll('#items-list>div').forEach(el => el.click()) in the address bar for those who are not familiar with JavaScript. That's why I put the button who allows us to select all items.
• the summary tab that keeps track of the number of items.
  • sometimes you want to know how many perfect gems you have when you type "Perfect" in the search bar.
• validation for the "Launch" button.
  • JavaScript say "you need to select at least one item", if someone try to click on the Launch Button without selecting any items.