additional commands (/npc help) for players and admins

NPC Packages can now be created for the NPC Provider
NPC faction definitions & relations are now generated from these packages

More information to prefabs being sold at trade stations

- Economy Stations that are in the territory (around or on planets) controlled by permanently hostile factions are now broken, burning and do not sell anything
- Delivery mission item amount are now calculated from the reward SC and the price of the superconductor
- Automatic PlanetaryHoldings management, system will add/remove PlanetSieges and PlanetaryOwners entries on the game load based on the planets present on the map. When planet is missing, it removes the entries as well, when new planet is found, it creates the entries and adds random NPC ownership
- Fixed faction reputation balancing on the game start
- Added Economy item price cache to all methods that calculate pricing for Economy Store Blocks and Vending Machines (should be a bit more performant)

Fixed methods which search for common enemies in mission encounters