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/ServerConnection.cpp

@@ -78,7 +78,7 @@ void ServerConnection::tick()
 	//            uc.disconnect("Internal server error");
 	//            logger.log(Level.WARNING, "Failed to handle packet: " + e, e);
 	//        }
-			if(uc->connection != NULL) uc->connection->flush();
+			if(uc->connection != nullptr) uc->connection->flush();
 		}
 	}
 
@@ -167,7 +167,7 @@ void ServerConnection::handleServerSettingsChanged(shared_ptr<ServerSettingsChan
 	{
 		for(unsigned int i = 0; i < pMinecraft->levels.length; ++i)
 		{
-			if( pMinecraft->levels[i] != NULL )
+			if( pMinecraft->levels[i] != nullptr )
 			{
 				app.DebugPrintf("ClientConnection::handleServerSettingsChanged - Difficulty = %d",packet->data);
 				pMinecraft->levels[i]->difficulty = packet->data;