Inventory Setup + Initial Item Implementation

[jhparkt]

Inventory / Item Implementation Branch

The hotbar is small right now because it is not scaled.

• Temporary Inventory UI
• Select item with keyboard (1,2,3,4)
• Drop item (Q) / Drops in front of where player is looking (may drop on walls...)
• Use item (E)
• Implemented instantaneous health potion (red potion)
• Implement potion with duration (orange potion / walks backward)
• Invisibility potion (white potion / open to implement anything else)
• Dynamic Inventory Size / Can be set in constants.cpp / No key mapping beyond 1,2,3,4 yet

Probably in the next PR:
Implement Spells
Other items such as keys for doors

[Tyler-Lentz]

This PR is super super cool! I like a lot how you have everything architected. This will be super fun to play around with and add new items.

I have a couple of misc comments for future PRs. These are just my initial thoughts and ideas so feel free to take and run with any of these you like, and not worry about others you don't. Also you might have already thought of some of these as well.

1. it might be worthwhile to make the inventory slot size something that can change. This could let us play around with items that increase inventory slots (backpack?), decrease slots (big items that take up multiple slots?) Also, even if within the gameplay we don't change this, it would make balancing the item slots easier if it was just one value we could change.
2. I'm assuming we'll have some other orange potions so the player doesn't always ignore orange potions
3. I think it would be good to display in text somewhere on the screen saying what happened after drinking a potion. For example, after drinking a nausea potion "You don't feel too good..." or it could just be "you drank a nausea potion". Right now it can be a little hard to figure out what happened, esp for the invisibility potion since you can't really tell that you are now invisible. This might not be a problem later on though if we have first person POV models so we can just make the hands go away, or potentially for the nausea potion we can make the screen tinted green or something like that.
4. we'll definitely have real potion models eventually, but maybe until then we could also color the cubes to be the color of the potion, which might make playtesting easier if we get to the MVP before we have the potion models.

THIS IS SO COOL!