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/DragonFireball.cpp

@@ -54,7 +54,7 @@ void DragonFireball::onHit(HitResult *res)
 			}
 			delete entitiesOfClass;
 		}
-		level->levelEvent(LevelEvent::ENDERDRAGON_FIREBALL_SPLASH, (int) Math::round(x), (int) Math::round(y), (int) Math::round(z), 0);
+		level->levelEvent(LevelEvent::ENDERDRAGON_FIREBALL_SPLASH, static_cast<int>(Math::round(x)), static_cast<int>(Math::round(y)), static_cast<int>(Math::round(z)), 0);
 
 		remove();
 	}