Project modernization (#630)

* Fixed boats falling and a TP glitch #266

* Replaced every C-style cast with C++ ones

* Replaced every C-style cast with C++ ones

* Fixed boats falling and a TP glitch #266

* Updated NULL to nullptr and fixing some type issues

* Modernized and fixed a few bugs

- Replaced most instances of `NULL` with `nullptr`.
- Replaced most `shared_ptr(new ...)` with `make_shared`.
- Removed the `nullptr` macro as it was interfering with the actual nullptr keyword in some instances.

* Fixing more conflicts

* Replace int loops with size_t and start work on overrides

Minecraft.World/SetEquippedItemPacket.cpp

@@ -20,7 +20,7 @@ SetEquippedItemPacket::SetEquippedItemPacket(int entity, int slot, shared_ptr<It
 	this->slot = slot;
 
 	// 4J Stu - Brought forward change from 1.3 to fix #64688 - Customer Encountered: TU7: Content: Art: Aura of enchanted item is not displayed for other players in online game
-	this->item = item == NULL ? nullptr : item->copy();
+	this->item = item == nullptr ? nullptr : item->copy();
 }
 
 void SetEquippedItemPacket::read(DataInputStream *dis) //throws IOException