Suppress warnings in Warpable.cpp with VC2012

We also define a typedef name GalaxyFieldCell in galaxy_fiel.h to
avoid writing explicit types in sources.
clib: Make UnZip.c do not depend on compiler int sizes

We also use alignment control directives for VC and gcc.
clib: Add a test program source to dump UnZip variable sizes
clib: Makefile accumulate CFLAGS given as env var
linux: Add svn-bullet.sh to checkout Bullet Dynamics Engine on Linux

There has been svn-bullet.bat for Windows, but not all Linux distributions
provide package managers with BDE support.

There are multiple ways to configure BDE: cmake, premake4 and autogen.sh.
We have been using premake4 for Windows, but cmake is recommended by
bullet/INSTALL, so we use cmake in Linux too.
Make the Makefile use local sources for Bullet and zlib

Previously, we have been using system-provided library headers to complie
the libraries, but not all systems have them or have package managers
available to install them easily.
Pass local zlib's include directory path to clib Makefile

The system could have zlib-devel package installed, but we prefer our
local version.
Merge branch 'clib' into next2
Add library paths for Bullet in GNUMakefile

If there is no system-provided Bullet Dynamics Engine libraries, we must
link the executable with local SVN checkout of BDE.  Also, we want BDE use
double precision for calculations, which may not be the case for system-
provided package.  Configuration for BDE will be done by svn-bullet.sh.
Make vastspace mod build with Makefile for linux gcc

We have not updated the Makefile since we had moved and renamed gltestdll
to mods/vastspace.  Now we'll fix this.
Add much information about building Linux server to README
Add gas giant texture for randomly generated planets
Make randomly generated planets rotate along orbit's axis

It seems natural that planets have rotation axis in the same direction
as the orbits.  We don't really know much about solar system formation
process, but at least angular momentum must be conserved.
Make Astrobj::absmag accessible from Squirrel scripts

Also assigned decent default values for Alpha Centauri and random
stars' absmag.
Add Rigil Centaurus B b, actual planet candidate to space_debug.ssd

It has about the same mass as the Earth, but not likely habitable
since it's on much closer orbit to the star.  The planet's surface
is speculated to be molten rock ocean.  Its orbital elements are
not accurate.

Rigil Kentaurus B a might be better deleted since there's no such
naming convention which gives "a" to a extrasolar planet in astronomy.
Make FindBrightestAstrobj capable of returning multiple Astrobjs

There could be multiple stars that illuminate planets in a binary
solar system.  We need a way to obtain a list of brightest Astrobjs
instead of just one.  FindBrightestAstrobj can do this by passing
more than 1 to resultCount.
Make DrawTextureSphere work with multiple lights

Now you can see a planet in a multi-star solar system lit with
multiple lights.
Make DrawTextureSpheroid capable of having multiple lights

We share some codes between DrawTextureSphere and DrawTextureSpheroid.

The texture rotation calculation seems wrong in DrawTextureSphere.
Random planets become oblate if they spin fast enough

The randomized parameters distribute around Saturn's characteristics,
so we could see planets as flat as Saturn.
Add moon textures and fix shaders for moon