Modernize project codebase (#906)

* 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

* Add safety checks and fix a issue with vector going OOR

Minecraft.Client/TitleScreen.cpp

@@ -18,7 +18,7 @@ TitleScreen::TitleScreen()
 {
 	// 4J - added initialisers
 	vo = 0;
-	multiplayerButton = NULL;
+	multiplayerButton = nullptr;
 
     splash = L"missingno";
 //    try {	// 4J - removed try/catch
@@ -93,7 +93,7 @@ void TitleScreen::init()
         buttons.push_back(new Button(4, width / 2 + 2, topPos + spacing * 3 + 12, 98, 20, language->getElement(L"menu.quit")));
     }
 
-    if (minecraft->user == NULL)
+    if (minecraft->user == nullptr)
 	{
         multiplayerButton->active = false;
     }