Modernize project codebase (#906)

* 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

* Add safety checks and fix a issue with vector going OOR

Minecraft.World/MinecartRideable.cpp

@@ -23,8 +23,8 @@ MinecartRideable::MinecartRideable(Level *level, double x, double y, double z) :
 
 bool MinecartRideable::interact(shared_ptr<Player> player)
 {
-	if (rider.lock() != NULL && rider.lock()->instanceof(eTYPE_PLAYER) && rider.lock() != player) return true;
-	if (rider.lock() != NULL && rider.lock() != player) return false;
+	if (rider.lock() != nullptr && rider.lock()->instanceof(eTYPE_PLAYER) && rider.lock() != player) return true;
+	if (rider.lock() != nullptr && rider.lock() != player) return false;
 	if (!level->isClientSide)
 	{
 		player->ride(shared_from_this());