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/NameEntryScreen.cpp

@@ -41,7 +41,7 @@ void NameEntryScreen::buttonClicked(Button button)
     if (button.id == 0 && trimString(name).length() > 1)
     {
         minecraft->saveSlot(slot, trimString(name));
-        minecraft->setScreen(NULL);
+        minecraft->setScreen(nullptr);
 //        minecraft->grabMouse();	// 4J - removed
     }
     if (button.id == 1)