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/JoinMultiplayerScreen.cpp

@@ -7,7 +7,7 @@
 
 JoinMultiplayerScreen::JoinMultiplayerScreen(Screen *lastScreen)
 {
-	ipEdit = NULL;
+	ipEdit = nullptr;
 	this->lastScreen = lastScreen;
 }
 
@@ -55,7 +55,7 @@ void JoinMultiplayerScreen::buttonClicked(Button *button)
         vector<wstring> parts = stringSplit(ip,L'L');
         if (ip[0]==L'[')
 		{
-            int pos = (int)ip.find(L"]");
+            size_t pos = ip.find(L"]");
             if (pos != wstring::npos)
 			{
                 wstring path = ip.substr(1, pos);