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/ContainerSetContentPacket.cpp

@@ -20,11 +20,11 @@ ContainerSetContentPacket::ContainerSetContentPacket()
 ContainerSetContentPacket::ContainerSetContentPacket(int containerId, vector<shared_ptr<ItemInstance> > *newItems)
 {
 	this->containerId = containerId;
-	items = ItemInstanceArray((int)newItems->size());
+	items = ItemInstanceArray(static_cast<int>(newItems->size()));
 	for (unsigned int i = 0; i < items.length; i++)
 	{
 		shared_ptr<ItemInstance> item = newItems->at(i);
-		items[i] = item == NULL ? nullptr : item->copy();
+		items[i] = item == nullptr ? nullptr : item->copy();
 	}
 }