Build 0.5.0

Laying the groundwork for stuff to come.

- Tweaked placement of some UI elements.

- Stat allocation button has a new placeholder image, which changes color based on whether or not the player has points available to allocate.

- Added inventory button, although the inventory system doesn't exist yet.

- Added shop stages. The shops don't actually have anything to buy yet, but this will be implemented after the inventory/gear system is good to go.

- Added text at the bottom left to indicate the user's EXP