Prototype 0.6d

Another small update just to fix up some things. There will be at least one more update to finalize some things, and then I'm going to start working on the main map as well as a main menu.

In this version:

- Skateboard sounds
- Slightly increased movement speed for walking, running, and skating
- You must now buy items from the NPC.
- Items now stack in inventory
- New sprites for the skateboard and chocolate bars
- GUI changes
- Net worth now updates and is (so far) based on how much cash you have
- Made the NPC movement more smooth

Future plans:

- More sounds
- Continue working on inventory system
- Continue working on shopping system
- Combat testing (not exactly sure how I want to make it yet)
- More GUI changes?
- Start development on the main map of the game
- Main Menu
- Character creation