Fixed a serious typo with buttons.

When destroyed was being called on a button it first called GameObject.init, it should've been calling GameObject.destroy.
Added upgrades.js. Testing out upgrade value retrieving.
Basic upgrade creation.
General upgrades can now be purchased from the smith menu.
Added perks.
Added tabs in the smith menu. Implementing weapon upgrades.

There's currently a bit of reuse in the menus. This is temporary since we just need a quick testing environment.