Added signal dialog that opens when clicking on a signal a second time. You can set the load orders from here, and is the only way to configure cargo specific orders.

Added support for resource-specific loading and unloading orders. This makes it much more feasible to use multi-cargo trains if you want to.

Updated the load and unload icons to be clearer. Now they are real icons instead of text with < > ? and | characters overlaid.

Fixed ordering of regions in scores dialog to make more sense in terms of unlock order.