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/AddEntityPacket.cpp

@@ -32,9 +32,9 @@ void AddEntityPacket::_init(shared_ptr<Entity> e, int type, int data, int xp, in
 		if (xd > m) xd = m;
 		if (yd > m) yd = m;
 		if (zd > m) zd = m;
-		xa = (int) (xd * 8000.0);
-		ya = (int) (yd * 8000.0);
-		za = (int) (zd * 8000.0);
+		xa = static_cast<int>(xd * 8000.0);
+		ya = static_cast<int>(yd * 8000.0);
+		za = static_cast<int>(zd * 8000.0);
 	}
 }