fix for danger faction in station attack/defense missions

- new siege related AI tag for NPC ships
- new definition value for siege ships, which can appear in station defense and attack mission types

dynamic economy logging cleaned out

Free port license icon changed to be a datapad icon with extra something

- new admin command /npc economy blacklist, which automatically blacklists items in dynamic economy and also stuffs reasons why into your clipboard, which can help you finding the items which are only sold or only purchased by NPC factions.
- the same method is called automatically during init phase if the blacklist is empty and dynamic economy is enabled

- dynamic economy modifiers can be enabled (they are disabled by default)
- dynamic economy modifiers are added on top of the NPC faction economy modifier
- the configuration and tracking what was sold/bought (by NPC factions) and how much is stored in the new EconomyDynamic.xml
- min max modifier is configurable
- initial ratio can be tweaked, so the first few transaction do not shift prices wildly up and down

- first couple of /npc mission invite/leave hotfixes
- /npc mission leave will now hide the mission window if the leaving player is not the last player in the mission
- /npc mission invite will send latest mission information and mission step waypoint to the invited player

free port naming hotfix

expanded /npc mission invite command description in /npc help