LuaTable: Add {Get, Load}Map methods
Ship.cpp: Add a Ship::SpawnMissile(Missile *) method
LuaShip: Add a Ship:AIKamikaze binding.
Add a power argument to the Missile constructor

This argument defaults to -1 which is an invalid value (when the power
is negative, the constructor just uses the default values) not to break
the current API but only extend it.
LuaShip: Export a SpawnMissile method
Replace Ship:FireMissileAt C++ implementation by a Lua one.
LuaTable: pass the map by reference in LoadMap()
LuaTable: Add GetVector and LoadVector methods.
Merge branch 'luatable-getvector' into missile-lua
Ship:FireMissileAt: accept a slot number as a first argument
Ship.lua: Use a translation table to cope with the new ship names.
Cpanel: Use the Lua FireMissileAt function to fire the missiles.
Cpanel: Use the Lua functions to get the list of missiles.
Player.cpp: Emit the missile sound on missile spawning instead of firing.
Ship: Remove once and for all Ship::FireMissile.
Merge remote-tracking branch 'laarmen/missile-lua'

Conflicts:
	src/LuaShip.cpp
	src/Missile.cpp
	src/Missile.h
	src/Ship.cpp
Merge remote-tracking branch 'upstream/master' into missile-lua

Conflicts:
	src/Ship.cpp
Use the distance facilities for missile explosion.

This changes the behaviour of missiles : they now spawn without target,
and will explode whenever a body enters a 100m radius, to the exception
of the missile owner.
Missile: the missile must be armed before it starts actively scanning for targets

It still explodes on collisions and laser hits, though.
Add a Lua interface to arm a missile