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/FlyingMob.cpp

@@ -75,7 +75,7 @@ void FlyingMob::travel(float xa, float ya)
 	walkAnimSpeedO = walkAnimSpeed;
 	double xxd = x - xo;
 	double zzd = z - zo;
-	float wst = (float) sqrt(xxd * xxd + zzd * zzd) * 4;
+	float wst = static_cast<float>(sqrt(xxd * xxd + zzd * zzd)) * 4;
 	if (wst > 1) wst = 1;
 	walkAnimSpeed += (wst - walkAnimSpeed) * 0.4f;
 	walkAnimPos += walkAnimSpeed;