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/SetEntityLinkPacket.cpp

@@ -18,7 +18,7 @@ SetEntityLinkPacket::SetEntityLinkPacket(int linkType, shared_ptr<Entity> source
 {
 	type = linkType;
 	this->sourceId = sourceEntity->entityId;
-	this->destId = destEntity != NULL ? destEntity->entityId : -1;
+	this->destId = destEntity != nullptr ? destEntity->entityId : -1;
 }
 
 int SetEntityLinkPacket::getEstimatedSize()