Adding toString for convenience

Remaining bugs til pull request:
* Items disappear when moving them back to the stage/forward
* Hud buttons not working as intended
Fixed items disappearing, but the stack issue is apparent now

Remaining bugs til pull request:
* Stack will try to put all of its items on instead of just 1
* Hud buttons not working as intended
Refactored out as many GameInstance references as possible

Remaining bugs til pull request:
* Stack will try to put all of its items on instead of just 1
* Hud buttons not working as intended
Fixed new bug: valid product wouldn't clear when removing items individually

Remaining bugs til pull request:
* Stack will try to put all of its items on instead of just 1
* Hud buttons not working as intended
TRIUMPHED OVER ITEMS DISAPPERING ON SECOND STAGE

Remaining bugs til pull request:
* Hud buttons not working as intended