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/MenuBackup.cpp

@@ -15,7 +15,7 @@ MenuBackup::MenuBackup(shared_ptr<Inventory> inventory, AbstractContainerMenu *m
 
 void MenuBackup::save(short changeUid)
 {
-	ItemInstanceArray *backup = new ItemInstanceArray( (int)menu->slots.size() + 1 );
+	ItemInstanceArray *backup = new ItemInstanceArray( static_cast<int>(menu->slots.size()) + 1 );
 	(*backup)[0] = ItemInstance::clone(inventory->getCarried());
 	for (unsigned int i = 0; i < menu->slots.size(); i++)
 	{