Neutral defense missions planning

These are updates of the Defend the System missions written for 0.3.x: dts_00, dts_01, and dts_02. They are being adapted to suit the large systems and jump point travel, and to take advantage of more API functions.

The planning part: Elderman (that's me) has taken change of revising these missions. But ideas, programming help, suggestions, criticism, is all welcome. Comment here, on the forums, or in irc: #naev on freenode.

Neutral defense mission 1
The backstory: a minor pirate clan are attacking a system on the fringes of the empire. They aim to execute a protection racket, threaten to disrupt trade to the system unless they recieve a bounty from the local governors. They jump in, stop all traffic through a jump point, then jump out again before they receive too much damage. The player gets caught up in the violence. The mission begins when the player jumps in from the direction away from the centre of the empire.


 * Stage one: an independent ship hypers in after the player, 'big pirate gang inbound, help, help, help. Please respond.'
 * Stage two: the player hails, is told to go get help at the nearest inhabited planet.
 * Stage three: The player goes to the nearest inhabited planet. On landing, player joins an impromptu defense fleet.
 * Stage four: The fleet returns to the jump-point that points away from the empire to chase away the pirates.
 * Stage five: the player returns to the planet for a reward.

Neutral defense mission 2
The backstory: the same minor pirate clan gets smarter. They choke off all trade in the direction of the empire. The player gets caught up in the violence. The mission begins before the player jumps in from the direction of the centre of the empire.
 * Stage one: an empire warship interrupts the player's jump to the next system. The jump point is occupied by pirates from the other side, the Imperial commodore tells the player.  She instructs him to recruit as many other independent ships as possible in the next X amount of time.
 * Stage two: the player hails as many ships as possible in the next X amount of time. The empire ship does the same.  Each ship the player hails becomes two who join the defense force.
 * Stage three: The player and the impromptu defense fleet hyper into the next system and chase the pirates away, optionally pursuing them to the jump point on the far side of the system.
 * Stage four: The player and the fleet go to an inhabited planet for their reward.

Neutral defense mission 3
The backstory: the same minor pirate clan gets smarter again. They choke off all trade in and out of the system, gathering around each jump gate. The player  gets caught up in the violence. The mission begins in the bar on a planet in the system.
 * Stage one: a messenger bursts into the bar and announces that pirates have completely stopped all traffic in the system. Two young navy cadets organize a sortie to break the pirates' hold on the system.
 * Stage two: the player and the impromptu defense fleet take off and eliminate pirates at each port in the system at at each jump point, finishing with the one the pirates enter from.
 * Stage three: The player and the fleet return to the beginning planet for a reward.