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/HeavyTile.cpp

@@ -60,7 +60,7 @@ void HeavyTile::checkSlide(Level *level, int x, int y, int z)
 				return;
 			}
 
-			shared_ptr<FallingTile> e = shared_ptr<FallingTile>( new FallingTile(level, x + 0.5f, y + 0.5f, z + 0.5f, id, level->getData(x, y, z)) );
+			shared_ptr<FallingTile> e = std::make_shared<FallingTile>(level, x + 0.5f, y + 0.5f, z + 0.5f, id, level->getData(x, y, z));
 			falling(e);
 			level->addEntity(e);
 		}