Changed the DIY-nerds system to Basic Small Systems.

This is more in line with what was being done in 0.5.3: it's not
worth very much, but it's *something*. I don't think having a 40%
chance of a mission literally giving you absolutely nothing is a
good idea.
Replaced fuel_consumption stat with fuel_consumption characteristic.

fuel_consumption is a flat variable, but ship stats are clearly
meant to be midifiers. This resulted in the game telling the player
that fuel_consumption was a modifier. It's now a (mandatory)
characteristic of the ship instead. This also avoids the problem of
the arbitrary 100 fuel default consumption.

Ships haven't been updated yet. That will be done next commit.

I also removed a bunch of ship info from the shipyard that is
outdated (i.e. characteristics that are no longer used, and that are
now determined by outfits and ship stats).
Updated all ships to use fuel_consumption, with one exception.

I didn't update the Reverance because that ship needs other updates
to it as well. It seems to have been left behind when the core
systems were added.

Conflicts:

	dat/ships/flf_lancelot.xml
	dat/ships/flf_vendetta.xml
Updated Sirius Reverence.
Reverted the removal of ship info.

I've decided that I'm not in favor of removing this. Naev doesn't
use it, but Naev's engine is very flexible and I think it would be
nice for the engine to be used for other similar games; for this,
having the ability to give specific ships extra stuff can be useful.
Gave the Schroedinger back its big fuel tanks.

I'm guessing they were removed when the core systems thing was
added. I've added them back. Well, I've added something like that
back. The Schroedinger now has 800 fuel units in its base form.
Added a description to Steiner.
Changed planet classes from enum to plain strings.

The Naev engine wasn't doing anything in particular with explicitly
defined classes. If anything were to be done, it would be in Lua,
and that only sees strings anyway. Just changing it to strings makes
it more flexible without losing anything.
Merge branch 'uhrabi' of https://github.com/onpon4/naev into tmp
Merge branch 'curgen_nerds' of https://github.com/onpon4/naev
Reverted armor stats to the units it was using before.

I think these measurements look silly, but whatever.
Merge branch 'bugfix' of https://github.com/onpon4/naev into tmp
Merge branch 'master' of https://github.com/bobbens/naev into economy