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/SignUpdatePacket.cpp

@@ -66,6 +66,6 @@ int SignUpdatePacket::getEstimatedSize()
 	l+=sizeof(byte);
 
 	for (int i = 0; i < MAX_SIGN_LINES; i++)
-		l += (int)lines[i].length();
+		l += static_cast<int>(lines[i].length());
 	return l;
 }