New spawner config attribute to limit maximum number of random spawns

forgotten null check during the first Provider init

- WeaponCore dependency is now optional, NPC ships will seek targets, respond to threats and fire even without it
- Reworked data cleanups when NPC packs are being added end removed. This is done during the init phase and should purge values from the PlanetaryHoldings, PersistentData, FactionOverrides and cleans out headquarter economy stations assigned to non-existent factions.

function which calculates the price of the grid now counts the internal inventories as well.

more formatting fixes

formatting fixes

more information about the grids being sold by trade stations.