Added screen handler system (#888)

* Added screen handler value

* Added screen handler constructor and function to show to player

* Made inventory_* functions work with screen handlers

* Event callbacks and some refactoring

* Exception if screen has no inventory

* Fixed NPE

* Close screen when null

* Added screen_property

* UNKNOWN_SCREEN throwable

* Fix error when not specifying click callback

* Access to non-container screen handler slots via the inventory_* functions

* Change lectern page

* Added button event

* Added 'close' event and refactoring callback

* Beacon and Brewing screens

* Cartography table screen

* Crafting screen

* Enchantment screen

* Grindstone

* Loom

* Merchant

* Shulkerbox

* Smithing table

* Stonecutter

* Use strings as screen type instead of ScreenHandlerType

* Remove support for multiple players

* Combining create_screen and open_screen and refactoring

* Allow modifying cursor stack

* Cleanup

* Docs

* Added multiple screen examples

* Rename to screen

* Added smoker and blast furnace

* Serialize screen content

* Store host name instead of context

* Add button value special cases to docs

* Spelling and grammar fixes by @James103

* Optimize screen inventory access

* Use -1 for slot click outside the screen

* As boolean, ScreenValue equals isOpen

* Revert "Use -1 for slot click outside the screen"

This reverts commit 68c113e71bb653191cedf4cc356ab7705838dc25.

* Rework of callback function

* Improve screen functionality with drop_item

* Editor keywords

* Only check syncId

* slot_update event callback

* Screem typo

* Mistake

* toTag returns "null" NBT for  closed screen

* Use null for slot index of -999

Co-authored-by: replaceitem <replaceitem.mc@gmail.com>

docs/scarpet/resources/editors/npp/scarpet.xml

@@ -71,6 +71,8 @@
 
                 team_add team_list team_remove team_leave team_property
 
+                create_screen close_screen screen_property
+
                 bossbar
 
                 player spawn entity_id entity_list entity_area entity_selector query modify entity_event entity_load_handler entity_types