display stacksize in the quickbarinventory menu now
have the client send a request to equip the quickbar slot when it's

selected
server now receives client request to select quickbar inventory slot

and does so
make the server ignore if a client requests to select a qucickbar index

that is out of bounds, and print a warning for it.
means that either there is a sync error, or that someone has malicious
intent, and do nothing.