Refund on upgraded units change + Spawn Event for upgrade change

Just two small tweaks:

  • When you refund an upgraded unit, you now get the full cost of the base unit + upgrade back. So upgraded filters should now give back 1.5 cores when refunded at full HP.
  • When you upgrade a unit there is now a spawn event that has the unit type as 7 (the upgrade unit type). The event also mentions what position the upgrade occurred on so you can see what was upgraded.

Thanks! This will certainly make the upgraded destructors more useable.