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/BaseAttributeMap.cpp

@@ -24,7 +24,7 @@ AttributeInstance *BaseAttributeMap::getInstance(eATTRIBUTE_ID id)
 	}
 	else
 	{
-		return NULL;
+		return nullptr;
 	}
 }
 
@@ -50,7 +50,7 @@ void BaseAttributeMap::removeItemModifiers(shared_ptr<ItemInstance> item)
 			AttributeInstance* attribute = getInstance(it.first);
 			AttributeModifier* modifier = it.second;
 
-			if (attribute != NULL)
+			if (attribute != nullptr)
 			{
 				attribute->removeModifier(modifier);
 			}
@@ -72,7 +72,7 @@ void BaseAttributeMap::addItemModifiers(shared_ptr<ItemInstance> item)
 			AttributeInstance* attribute = getInstance(it.first);
 			AttributeModifier* modifier = it.second;
 
-			if (attribute != NULL)
+			if (attribute != nullptr)
 			{
 				attribute->removeModifier(modifier);
 				attribute->addModifier(new AttributeModifier(*modifier));