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/Snowball.cpp

@@ -31,7 +31,7 @@ Snowball::Snowball(Level *level, double x, double y, double z) : Throwable(level
 
 void Snowball::onHit(HitResult *res)
 {
-	if (res->entity != NULL)
+	if (res->entity != nullptr)
 	{
 		int damage = 0;
 		if ( res->entity->instanceof(eTYPE_BLAZE) )