Another pirate bounty mission replacement.

Actually, I replaced my previous pirate bounty mission replacement
with two missions: the "Dead or Alive" bounty mission, and the "Alive"
bounty mission. Both of these require a new "Mercenary License".

Conflicts:

	dat/missions/neutral/pirbounty.lua
Fixes for the bounty mission.
Make same-system bounty pirates spawn in a random location.

Same-system bounties, with the ships spawning right next to you, are
too prone to excessive grinding. With that in mind, same-system
pirates now spawn in a random location within the system, making you
have to look for them and also making their death by other ships
more likely.
Make jumps_permitted work on landing as well.
Make Alive bounties cost more than Dead or Alive bounties.
Make bounty missions appear less frequently.
Make Alive bounties even higher.

Capturing a pirate is much harder than killing them: you need to
bring along non-lethal weapons, which leaves you more vulnerable,
and you need to hope any local police don't kill the pirate anyway.
Alive bounties have been raised further to compensate for this.
Fixed bounty missions not giving rewards.
Make the bounty mission levels based on the number of pirates.

So, systems with few pirates will only ever have tiny bounties, and
systems with a moderate number of pirates will never have more than
moderate bounties.
Don't have very small bounties in systems with lots of pirates.

This makes the missions more consistent. It can be annoying if you
get tiny or small bounties when you went to an area with lots of
pirates specifically so you could get high bounties.
Added pay text choices.
Reduced the maximum distance to search for bounties.
Moved the condition for the bounty missions to its proper place.
Fixed warnings with bounty missions.
Change the ship of a captured pirate to "dummy".

Previously I was grabbing it with pilot.control, which woked, but
this makes more sense.
Added the mercenary license to "all outfits".
Added Mercenary License to some techs, so it can be aquired.
Changed the way pirates in the pirate bounty mission are positioned.