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.Client/SlimeModel.cpp

@@ -27,9 +27,9 @@ SlimeModel::SlimeModel(int vOffs)
     }
 	else
 	{
-		eye0 = NULL;
-		eye1 = NULL;
-		mouth = NULL;
+		eye0 = nullptr;
+		eye1 = nullptr;
+		mouth = nullptr;
 	}
 	cube->compile(1.0f/16.0f);
 }
@@ -39,7 +39,7 @@ void SlimeModel::render(shared_ptr<Entity> entity, float time, float r, float bo
     setupAnim(time, r, bob, yRot, xRot, scale, entity);
 
     cube->render(scale,usecompiled);
-    if (eye0!=NULL)
+    if (eye0!=nullptr)
 	{
         eye0->render(scale,usecompiled);
         eye1->render(scale,usecompiled);