create the 'switched tooltip' document, currently literally a mouse cursor

but it locks to the position of currently selected quickbar slot.

also cleanup a lot of the code with more clean/condensed versions in the
quickbar stuff. mostly strings and int-to-strings.

oh and there's std::to_string, which is badass
initial text for quickbar switched tooltip
cleanup more quickbar code
cleanup Element calls
switched tooltip alignment fixes and hides after a duration after switch

fix max equipped item usage; already defined in quickbarinventory

it's mostly done, just need to set the text of it at runtime.
set the name of the switched tooltip when it switches

if there's no item at that slot obviously we shouldn't show it
add a fixme